Monday, August 27, 2007

An Idle Threat

Part 1 of a five part series on Pune City and environment. Updated every Tuesday.

I cross Law college road everyday on my way to soccer practice. The traffic is an endless stream, and sometime back I told the other coaches that I will be coaching from the other side of the road. At the Prabhat road signal and at Nul stop the back-up is so bad, you could easily miss 3 or even 4 signals before crossing the intersection. Urban legends about these backups are growing. Just last week a woman gave birth in her car waiting for the signal. Most vehicles keep their engines idling during their wait. That gave me the idea for this blog. How much pollutants does your vehicle emit when you wait for a few minutes at a traffic signal? How much does the entire city of Pune emit?

I first had an inkling that the amounts were big when I noticed at truck stops in the U.S. that the truckers never shut down their engines. A little web research told me this astonishing fact:

Trucks in the United States consume about 1 billion gallons of diesel annually while idling! This amounts to about 11 million tons of CO2 emitted annually (Source: U.S. Dept. of Transportation). Overall the transport system in the U.S consumes 8.4 billion gallons of fuel annually while idling. This amount to about 83 million tons of CO2 emitted annually while idling.

Edit: Based on EPA chemistry of fuel combustion 1 billion gallons will emit about 10.1 million tonnes of CO2, but the EPA warns that "calculations and the supporting data have associated variation and uncertainty".

Using vehicle numbers from the Pune Municipal Corporation Env. Status Report, emission factors for various pollutants from a World Bank study and some assumptions about mileage and idling times I did some calculations for Pune. The numbers do not give any comfort.

On a daily basis, assuming a vehicle idles for just 2 minutes every day:

The total fuel consumed in Pune by idling cars, two wheelers and rickshaws amounts to an incredible 19 thousand litres per day! Emissions of greenhouse gases amount to 45 tonnes/day.

How much do all of us on an individual basis contribute? Graphs below estimates how much fuel is consumed and how much CO2, PM10 and SOx is emitted by your vehicle every year if you idle your engine for just 2 minutes every day waiting for the light to turn green.

So, if you drive a regular car you probably lose about Rs 500/- or so yearly on fuel burnt while idling. This 2 minutes is a very conservative estimate I used to do the calculations. Idling time may well be much more. For example, idling your car for 5 minutes every day, you will spend about Rs 1250 per year in fuel burnt and so on. Something to think about next time you are waiting for the light to turn green at a busy intersection. How do you make people change their habits? One way is to appeal to their civic sense, and the other in my opinion the more effective, is to make them aware of the costs of their behavior.

See, where I am going with this? If I alone spend Rs 500/- how much for the entire city? Table below shows how much the city of Pune is paying yearly in terms of fuel lost, CO2, PM10 and SOx emitted, and fuel cost for vehicle idling. This is for total number of cars, two wheelers and rickshaws in Pune, assuming an idling time of 2 minutes every day.

For readers outside India, 1 crore = 10 million, so Pune city spends Rs 34 crore or Rs 340 million worth of fuel burnt while idling. If all vehicles in Pune reduce idling time by just one minute per day we would save about 3.4 million litres of fuel worth about Rs. 17 crore annually! This is equivalent - in terms of fuel saved and CO2 emitted - to removing around 18,500 two wheelers or about 9,300 cars from the roads of Pune.

By the way, you can learn more about idling and various myths using this website from the Canadian Office of Energy Efficiency, designed specifically to help individuals, communities, businesses reduce vehicle idling and pollution.

Thursday, August 23, 2007

Artificial Life and ....Debates

The Times of India carries a weekly debate called view and counterview. This week (Aug 23 2007) it was about the possibility that scientists may be able to create artificial life in the next decade or so. The very nature of the format means that the debate takes a predictable path of presenting two extreme points of view. In this case, either artificial life is great or it is the ultimate evil, either "synthetic life is going to be man's crowning achievement, his greatest work of art, or " renegade super bugs could, like locusts , destroy everything they come in contact with". Is this really the point of view of the reporters? Have they clarified their personal positions on this issue, and does the public know whether these reporters have held consistent views in the past. Without this knowledge, I as a reader feel this debate on artificial life is ....just a bit too artificial. Instead of having a contrived debate with two people shouting past each other, why not invite a biology ethics expert to write on this immensely complex issue?

Then there are the inevitable bloopers about evolution. Narayani Ganesh who wrote against artificial life writes " recent outbreaks of diseases caused by viruses like West Nile flu', AIDS, avian flu', and SARS (Severe Acquired Respiratory Syndrome) are very likely the outcome of unnatural or artificially created mutations that have manifested as contagious and life-threatening diseases with no tested cure". This is a very strange point of view. Pathogens like any other life forms mutate at a natural rate and may occasionally evolve a life strategy that may harm humans. There is no evidence that human activities are inducing mutations in viruses and making them more harmful than they otherwise would be. A large body of empirical work has disproved such notions of directed mutations. It is true that in the modern era, diseases which previously may have been restricted to isolated communities are finding their way into the global population, but that simply means that more people are in danger of being exposed to a naturally evolving pathogen.

Later in his article Mr. Ganesh says" maverick attempts to leapfrog evolution- bypassing natural checks and balances- could well prove to be our nemesis". These kind of statements are inspired by thinking of the earth as some kind of self-regulating entity, a concept made famous by James Lovelock and his Gaia hypothesis. But evolution does not necessarily lead to any natural checks and balances. A virus may simple decimate a population of humans or some other creature not because nature has some kind of self-regulating population control measure that returns it to an "equilibrium" state, but because the virus has locally evolved a successful strategy of reproducing itself. The reporting on evolution continues to be uninformed.

Tuesday, August 21, 2007

Plate Tectonics and Energy Politics

I came across a couple of good articles in on climate change. The first was a somewhat radical position taken by Freeman Dyson. In his opinion, the effects of climate change are exaggerated and can be mitigated by changes in land management and farming practices such as no-till farming and genetically engineering plants to create more root biomass, essentially increasing carbon stored in soil. He has some especially unkind things to say about computer models of climate change. This brought out a response from Alun Anderson, who invited Dyson to come to the Arctic and take a look for himself. A good give and take. Anderson mentioned that summer melting of Arctic ice has increased and this has resulted in a mad rush by Russia, Canada and Denmark to map accurately the continental shelf bordering their coastline.

What's the big deal about continental shelves? The five countries bordering the Arctic (U.S, Canada, Denmark who administers Greenland, Norway and Russia) have exclusive right over mineral deposits extending to 200 nautical miles from their coasts. This zone can be extended if any country can prove that their continental shelves extend to a distance more than 200 miles. Russia is now claiming just that. It is saying that the Lomonosov ridge which is an underwater linear block of continental crust aligned roughly NE-SW is a natural extension of its continental shelf. Preliminary estimates suggest that the ridge could yield about 10 billion barrels of hydrocarbons.

Plate tectonic theory has been used to explain the geological evolution of terrains, but this is probably the first time it has been called upon to resolve a brewing political crisis.


In early Tertiary period (about 50 million years ago) the north Atlantic spreading ridge propagated northward (dotted purple line and arrow). This cause the continental shelf of Eurasia to rift and split apart. This rift evolved into a oceanic spreading ridge known as the Gakkel ridge (spreading shown by yellow arrows). The Lomonosov ridge is a linear block of Eurasian continental shelf which split and moved NW to its present position. Russia asserts that its Siberian continental shelf extends naturally as the Lomonosov ridge. The point of contention is highlighted by a red arrow next to the label Russia. Is there is geological continuity of terrains there? Plate tectonic theory suggests that the ridge was moved there into position and juxtaposed against the Siberian shelf. Recent seismic data show that as the ridge approaches Siberia it deepens and there are buried faults in the deeper sediment between Siberia and the Lomonosov ridge, a finding that supports tectonic theory. Denmark and Canada can probably make a similar claim on it's side of the Lomonosov ridge.

But why should that matter? Currently reality should take priority. Even if the ridge was originally somewhere else and stuck on to the Russian shelf later by plate movements, doesn' t that make it a natural extension of the Russian shelf. The law of the sea doesn't say which type of geological process should cause the extension of the shelf. I have a feeling Denmark will also be able to show that the Lomonosov ridge is attached to their shelf. As warming clears more Arctic ice, plate tectonic theory will have plenty to say on the complicated energy politics of the Arctic ocean.

Saturday, August 18, 2007

Evolution: A Great Mystery?

Live Science , an online science news portal is carrying out a "greatest mystery" series, in which they are asking prominent scientists from various fields to talk about the unknowns. With a series title like this, it is inevitable that the chosen scientist and the reporter will play up the 'mystery' part and give the impression that scientists are pretty much befuddled. For the theory of evolution , the scientist interviewed (Aug 16 2007) was Massimo Pigliucci of the Department of Ecology and Evolution at Stony Brook University in New York. T. Ryan Gregory has dissected the interview in his blog and pointed out the various misunderstandings that it created regarding the state of our understanding about evolution. I will add just one more impression. The interviewer writing about various evolutionary "forces" says

Self-organization is another evolutionary force that some experts say whips up complex features or behaviors spontaneously in living and non-living matter, and these traits are passed on to offspring through the generations.

"A classic example outside of biology are hurricanes: These are not random air movements at all, but highly organized atmospheric structures that arise spontaneously given the appropriate environmental conditions," Pigliucci said. "There is increasing evidence that living organisms generate some of their complexity during development in an analogous manner."

The example given of a spontaneously arising complex structure is protein folding. Proteins take on endless shapes and the mechanism that triggers this form is a chemical signal.

I have always felt that reports like these neglect to explain the distinction between proximate causes and ultimate causes. Proteins do fold spontaneously, but proteins serving a particular function always fold the same way. So in trillions of cells in trillions of different organisms, something is controlling the consistency of the chemical signal and therefore the shape the protein. That something is the gene(s) that codes for the signal. Which means that over time evolution has populated the world with only those genes that code for just the right chemical signal. The process that causes such an accumulation of the right genes is natural selection.

Biologist may not today understand the mechanics of protein folding (proximal causes), but they accept that natural selection has to be the ultimate cause. In this case I feel Massimo Pigliucci fudged the part of ultimate causation and exaggerated the mystery of proximate causation. The level at which such apparent mysteries exists needs to be clarified by the interviewed scientist. It would be too much to expect from the media.

Thursday, August 16, 2007

Indians Predated Newton

Lord Ram flew in the Pushpak airplane on his way from Lanka after his victory

The Kaurav Princes were test tube babies.

Arjuna used what amount to nuclear weapons in the battle of the Mahabharata.

All patriotic Indians are well aware that ancient India was the source of all human knowledge. But somehow we were too forgetful, too careless, too lazy to do anything about it and over time this priceless knowledge was lost.

Now it appears we were too generous. A Kerala school of mathematics having discovered the infinite series, one of the basic components of calculus in around 1350 A.D. passed it on to Jesuit Missionaries in 1500's. The Jesuit's held on to the secret for more than 100 years, until they spotted Newton struggling. Taking pity on him, they explained the infinite series to him. Newton promptly invented calculus.

Jokes apart, new research does appear to show that Indians had discovered the infinite series in around 1350 A.D. According to Dr. Joseph of the Univ. of Manchester, who made the discovery while trawling through obscure Indian papers for a yet to be published third edition of his best selling book 'The Crest of the Peacock: the Non-European Roots of Mathematics' by Princeton University Press.

"The beginnings of modern maths is usually seen as a European achievement but the discoveries in medieval India between the fourteenth and sixteenth centuries have been ignored or forgotten.

"The brilliance of Newton's work at the end of the seventeenth century stands undiminished - especially when it came to the algorithms of calculus.

"But other names from the Kerala School, notably Madhava and Nilakantha, should stand shoulder to shoulder with him as they discovered the other great component of calculus- infinite series"

Read the complete press release.

Due to the Independence day holiday, most Indian newspaper haven't covered the story yet although its slowly making its way in the blogosphere. I am waiting for the reactions of the Vishwa Hindu Parishad .

Wednesday, August 15, 2007

Temples and Urban Sprawl

Read this press report on Ankor Wat. The famed temple complex in Cambodia, now surrounded by rice fields and forests was once in the centre of an urban sprawl. The population of the sprawl could have been as high as half a million. (image to the left from bbc website)

The archaeological research paper was published in latest issue (Aug 14 2007) of the Proceedings of the National Academy of Sciences.

"We now know that instead of being just (a collection of) temples, Angkor was actually a continuous and interconnected network of temples and small scale residential features like small village ponds, small village temples as well," said Damien Evans of the University of Sydney. "Very little remains now, they are just piles of brick ... a thousand years ago (it) would have been a huge and popular city, full of life, rather than this image of temples in a jungle."

The researchers think that this large urban complex was abandoned due to over population, deforestation and top soil erosion due to intensive agriculture.

I thought I'd post a few images of temples in Pune, surrounded by various levels of urban sprawl. Images are about 2 years old.

Balaji Temple, Sus Road
Red arrow points to temple. Still some open fields surround this temple. This is a good example of the conversion of agricultural zones into urban built up. Couple more years and the temple is likely going to be surrounded by a concrete jungle.

Vitthal Mandir, Vittalwadi
The famous Vitthal Mandir, which used to be so out of the city. Now right next to the busy growing townships surrounding Sinhagad road .

Dadgushet Halwai, Ganapati Temple

In the heart of old city, Pune. This temple was built in the crowded city centre.

Ganapati Temple, Sarasbaug.

This one was built on the then outskirts of the city during the reign of the Peshwa's in the late 1700's. Now in the heart of the city.

Can't think of anything profound to say, so that's it.

Tuesday, August 14, 2007

Journey without Maps

India's science laureate , Prof. Jayant Narlikar recently wrote an excellent column in the Times of India (July 28 2007). He writes about accurate maps or the lack of them. For a country obsessed with secrecy, revealing one's true location is anathema. Disorientation is easier to manage. He correctly points out that the word "information" doesn't equate with IT and call centres alone. Our citizens have a right to good geographic information i.e. accurate maps of cities, natural resources and navigational maps. This lack of maps and geographic data doesn't surprise me. Geographic information systems (GIS), the technology for creating, managing and analyzing spatial data is now a crucial component of the day to day work cycle of city, state and federal governments of many countries. In India, somewhere in the labyrinths of our mammoth bureaucracy, there are people whose sole job is to flip through magazines and make sure that boundaries of India in depicted maps are shown accurately. Only then can the magazine be circulated. Way to go India!

But I don't want to sound too negative. Change is on its way. The Govt. of India has set up a National Spatial Data Infrastructure, whose chief aim is to distribute data. They have even set up a website which is going to act as the data clearinghouse, where citizens will be able to query about a location and download available data. I checked out this website called NSDI for India. Looks well made but unfortunately it is an empty shell. All my searches came empty. I emailed them several times, but no reply either. Maybe someday.

There is another site where citizens can get data. This is a data clearinghouse set up by the Ministry of Environment and Forest known as Environmental Information Centre. It is a well designed, easy to use website. Users can specify the location and type of data they want, choosing from an available list. This data is not free. After the list is submitted, users will receive a quotation from EIC. I submitted a list of 7 standard data sets for an area around 200 sq km. The data set would have set me back by around Rs 85,000/-. Sounds expensive, but creating data is the main headache and expense of any GIS project. I think this is a very good resource in a country where good data is very hard to come by.

Finally Prof. Narlikar in his article talks specifically on city data sets. The kind you see in very high end cars in the U.S. and Europe where you can input your start and destination address and navigate using a digital display. Those data sets are enormously expensive to create and maintain since they need to be updated on a six month cycle. In the U.S they sell for tens of thousands of dollars for one city. Personal ownership of the data is too expensive even for Americans, but these datasets have made their way into applications that people use everyday. In India, they will probably be created by big private enterprises not just for car navigation but for the mobile phone market. The market is enormous and location based applications will inevitably be in high demand.

Monday, August 13, 2007

Adam's Bridge

This topic has generated a lot of controversy. Between Pamban, Southern tip of Tamil Nadu, India and Mannar, northern tip of Sri Lanka is the Palk Strait. Adam's Bridge is a chain of sand shoals and coral islands which appear as stepping stones along the Palk Strait . Everyone accepts that these are natural features. The controversy is whether there is a causeway linking these islands. Proponents of the causeway say that recent "studies" prove the presence of an artificial structure. This lends credence to the story in the epic Ramayan that Shri. Ram's army built a causeway in order to invade Sri Lanka and rescue Shri Ram's wife Sita. This causeway known as Ram Sethu, according to the proponents has since been submerged due to a sea level rise. Satellite pictures showing a milky white line connecting India and Sri Lanka have appeared in Wikepedia and also in the Indian blogosphere. The one above, of the Palk Strait is the NASA image that has contributed to the controversy. The perception of continuity is however an illusion caused by a combination of cloud cover and suspension of white calcium carbonate sediment along the length of the coral islands. The next image shows a close up of the Palk Strait. The discontinuous nature of the islands is clearly seen. The images are inconclusive on the issue of the causeway.

In the online magazine Rediff, there was an interview (July 31 2007) with Dr. Badrinarayanan, former director of Geological Survey of India and former coordinator of the survey division of the National Institute of Ocean Technology (NIOT), Ministry of Earth Science, in Chennai. NIOT recently drilled boreholes and recovered cores along the island chain. This has produced data more informative that satellite pictures. The cores are more than 10 metres thick and according to Dr.Badrinarayanan

"we found marine sands on top and below that was a mixed assemblage of corals, calcareous sand stones, and boulder like materials. Surprisingly below that up to 4-5 metres, again we found loose sand and after that, hard formations were there".

Dr. Badrinarayanan is clearly puzzled by this inter-layering of sand, boulder and coral and concludes that the boulders have to be artificially placed there, since there is no way they can appear on top on a marine sand layer. As a geologist who specializes in limestones, I can say that this sequence of sediment is exactly what you would expect from such a setting. The coral animal secretes a skeleton of calcium carbonate. Corals are colonial organisms, so hundreds of millions of such animals aggregate and secrete calcium carbonate skeletons. This, over time results in large structures which produce topographic highs on the sea bed. Such coral aggregates which show topography are called reefs. The shapes of these structures range from delicate branching types to more massive aggregates of carbonate material, some of which look like giant brains. As these structure grow upwards from the sea bed they encounter shallower water and start getting battered by waves. Particularly during storms, pieces of corals break off from the main reef.It is common for reefs to have an apron of debris composed of small and large boulders sitting on top of the sandy sea floor. In reef systems, sand is everywhere. The natural disintegration of coral skeletons upon death of the coral animal produces sand, erosion by waves produces sand, and additional sand can be transported from the surrounding continental shelf. In this case much of the sand is being brought by currents from coastal areas of India (Rameshwaram to Vedaranniyam coast) and Sri Lanka (Jaffna penninsula). This sand infiltrates the cracks and crevices of the coral structures and also blankets the sea floor.

Now, here is the crucial property of such very shallow water systems. They produce such vast amounts of sediment that they force a local change in sea level along with changes in currents. This means a certain type of sedimentary environment may in response to a shift in sea level encroach upon and bury an adjoining sedimentary environment. Corals can encroach and bury sand, just as sand can shift and bury adjacent coral and boulders. Over long periods of time such migrating and shifting environments will create a geological section, such as the one observed in Dr. Badrinarayanan's cores, a complex sequence of inter-layered sand, coral and boulders.

I suspect the sand shoals and the coral complexes represent a geologic history spanning the late Pleistocene to Holocene epochs (the last hundred thousand years). During the Pleistocene "ice-age" period, glacial buildup and melting forced fluctuations in sea-level by tens of meters , setting up the conditions for several episodes of coral reef and sand shoal formation. During periods of large sea-level drops in the Pleistocene, there would have been a land connection between India and Sri Lanka. But at the end of the last Wisconsin glaciation, the sea-level began to rise world-wide. This period of global sea level rise beginning around 10-12 thousand years ago marks the beginning of the Holocene epoch. The Palk strait became deeper as sea-levels rapidly rose by several ten's of meters in the early part of the Holocene. By mid-Holocene sea-level stabilized, and thereafter minor fluctuations in sea-level changes have been dictated by local geological processes more than any global control. It is important to understand where the Ramayan fits in within the context of all this history of sea-level changes. Mainstream historians place the Ramayan around 100-500 B.C, while the fringe historians place it as far back as 3000 B.C. Both parties though place it firmly within the mid-late Holocene, by which time the Palk Strait was certainly a few to ten's of meters deep. Dr. Badrinarayanan interprets the entire sequence in his cores as having formed in the mid Holocene, specifically from about 5800 to 4000 years ago. He bases this on coral reefs terraces on Rameshwaram island which give carbon dates ranging from 5400 to around 2600 years B.P. (before present). There is also recent coral in the low tide shorezone of Rameshwaram island. According to him, the causeway was built during a sea-level fall sometime in the last few thousand years, i.e in the mid Holocene, the boulders brought in by quarrying exposed coral rock in Rameshwaram. This may conjure up images of Pleistocene style sea-level falls of several ten's of metres, exposing much of the Palk strait sea-bed, leaving only few deeper patches to be filled up to form a causeway. But the coral reef terraces at Rameshwaram may be telling a different story. Reef growth track sea level change. So the successive reef terraces can be taken as an indicator of sea level change. The Rameshwaram reef terraces are about 1 to 1.5 meters above present sea level. This suggests that Holocene sea-level falls were probably not extensive enough to have exposed large parts of the basin. Plus there is the question of the timing of sea-level falls. I am not sure if there is an exposure surface between the older and younger terrace which would indicate that sea -level fell, exposed the sea bed and then rose again drowning the area and leading to the growth of the younger coral terrace. That would be an interesting find as it would give a solid date to the sea level fall and would provide more reliable evidence of the extent of Holocene sea level falls. At the moment the best we can say is that sea-level has been dropping sometime after the youngest dated exposed terrace around 2600 B.P. In any case I doubt if any sea level fall in the Holocene would have lead to any significant lowering of sea-level. Large stretches kilometers long would have remained under water metres deep, making causeway building an impossible exercise. In contrast, processes of coral reef formation in the Palk strait would have provided an in situ source for the natural formation of the debris and boulders found in the cores.

This is a controversial issue involving the religious sentiments of millions of Indians. I feel though that any detailed geological investigation of the Palk strait sediments will be able to explain Adam's bridge as a natural consequence of sand shoal formation and coral reef dynamics.

There are other natural processes by which boulders can appear on the sea floor. But that is a topic for another blog.

Friday, August 10, 2007

Chernobyl and Sexual Selection

This was fun to write about. A new study around Chernobyl has analysed the effect of radiation on bird health. Birds use antioxidants for a variety of activities. The research studied the health of birds which 1) migrate long distances 2) lay large eggs 3) Develop bright plumage using carotenoid, a type of antioxidant. All these three activities take up large quantities of antioxidants. Radiation creates free radicals which damages DNA. This damage can be limited if there are enough antioxidants in the body to soak up the free radicals. The researchers A.P. Møller and T.A Mousseau hypothesized that because birds in the above 3 categories had fewer antioxidants left to mop up dangerous free radicals, these birds would be most adversely affected by exposure to radiation around Chernobyl. Their hypothesis was supported by their test results.

The story was reported in a number of press releases (July 12 2007). The Economist has a different take on it. According to them the results cast light on the theory of sexual selection as well. This theory among other things tries to explain adornment and ornamentation in animals such as the peacock' s tail, bright plumage, the fantastic feathers of the birds of paradise. Such features are clearly detrimental to the bearers health. Why does the utilitarian process of natural selection allow such flagrant excess? Colorful plumage in birds is usually a sexual signal influencing mate choice. The signal may be arbitrary or it may be a sign of underlying good health or good genes. The Economist argued that since the carotenoid-based bright red and yellow plumage birds declined in health, the plumage really does come at a price indicating underlying good health.

But I think there is a problem with this argument. The report in the Economist was correct is saying that there is a debate in biology between those who think signals such as flashy feathers are essentially arbitrary and those who think they are signs of underlying health and good genes. Let's look at this using just female choice. In the "arbitrary" or "good taste" model first enunciated by R.A. Fisher, an initial bias towards a particular feature say bright color is set up by chance, essentially some females may take a fancy for a particular color. Because of this initial bias, natural selection will favor females who go along with the fashion because her son will inherit his father's bright color and her daughter will inherit her preference for bright color. This then sets an ever increasing evolutionary spiral of brighter colors in males and stronger discrimination for brighter color in females. The bright plumage develops because it acts as a label for sexual attractiveness. In this case even though being bright takes up large amounts of antioxidants, being fashionable by in itself is adaptive, since it leads to greater reproductive success.

In another model known as "good sense", the females actively are discriminating for underlying good health using bright color as an indicator. Loss of color may be an early sign of parasite infestation, so females can use brightness as a diagnostic tool. This will set up selection in males to deceive the female by false advertisement of bright color. In effect even an unhealthy male
who manages to produce a bright color will prosper. This in turn will set up a counter-selection in females to see through this deceit. Again male color and female discrimination will evolve, in evolutionary biologist Helena Cronin's memorable words, over generations "the females utilitarian stethoscope gradually burgeoning into a brilliant kaleidoscope". This model was modified into the "handicap" hypothesis by A. Zahavi who argued that advertisement has to be costly to reveal the true health of the male. Think of conspicuous consumption. If you buy an expensive car, it will cost you financially, but at the same time you are signalling to society that you are quite well off. What you lose in cash, you gain in enhanced social status and its benefits. In this sense, according to Zahavi females prefer the most handicapped males. In the "good sense" or handicap model only the healthiest males would be able to allocate large amounts of carotenoid antioxidants to color their feathers and still manage to stay alive at least long enough to reproduce.

After this long discussion, the conclusion is brief. The effect of both types of female choice ultimately results in bright plumage which means large usage of carotenoid which in turn imposes a health cost on the male. Carotenoid based plumage comes at a price regardless of which type of female choice produced it. So the harm to bright colored birds cannot be use to discriminate between the two hypothesis.

An interesting point to note here is that the original research although indicated that the bright plumage may be sexual signals, did not address the issue whether the decline in bright colored bird's health could be considered a test for the two models of sexual selection. This inference was drawn by the Economist reporter. I emailed my above objection to the science editor of the Economist. He was kind enough to write back saying "I do take your second point, though, that Fisher's original model can accidentally impose health costs. I shall investigate the matter further".

The first point was my objection that the bright color was a sexual signal in the first place. Sexual selection holds a special place in modern evolutionary theory. W.D. Hamilton one of the most influential evolutionary biologists of the 20th century once remarked, that if he understood why there are certain bird species in which both sexes are brightly colored, he would die happy. Unfortunately he died of a mosquito bite in March 2000 (complication due to malaria) without solving this mystery. The debate is sure to rage on in the coming years.

Early Man in India

Did Early Man Originate in India

Times of India May 30 2007. When I read the title I had a sinking feeling that this was one of the articles which pushed the "India is the origin of everything" agenda. And I was right:

"It may provide new clues to the history of mankind. A recent discovery by a city scientist working for the Anthropological Survey of India (ANSI) has strengthened the theory that the early man could have originated in India. It also hints at the possibility that central India might have been the hotbed of human evolution."

Apart from the use of quaint language "hotbed of human evolution" a term more appropriate in a sentence like " 36 Chowrangee Lane was the hotbed of Marxist revolutionary thinking", the article amazes with its mix of brazen theorizing and leaps of faith. The ANSI found a human femur (thigh bone) in Madhya Pradesh. It may or may not be about 50,000 years old. It may or may not be that of Homo erectus. But without confirmation of the age or taxonomic status of the fossil, the survey scientist Dr. Gangopadhyay announced that this will cause a radical change in our theories of where modern "man" presumably Homo Sapiens evolved. According to him this fossil along with a genetic signature common to peoples of the Indian subcontinent called M haplogroup is strong evidence that Homo sapiens originated in India and not Africa. [A genetic haplogroup is a small section of the genome with a unique set of genetic variations which is inherited as a unit. One such set of genetic variations termed M is commonly found in Indians and has been established not using fossils but by analyzing modern populations of humans (Homo sapiens) from different continents. Populations in different continents are characterized by other unique haplogroups].

How has Dr.Gangopadhyay come to this conclusion? I can only guess that his thinking is along the lines; since homo erectus is considered to be the ancestral species to homo sapiens and since the fossil shows the (possible) existence of erectus in India and since the M haplogroup is quite old (around 50 -80 thousand years), homo sapiens evolved from the homo erectus populations in India and then migrated elsewhere. A little history first. All scientists, even patriotic Indians readily accept that Homo erectus an earlier hominid species originated in Africa and migrated to Europe, Middle East, South and south east Asia more than 1 million years ago. Stone tools as old as 1.2 million years ago imply the presence of erectus in India, in the Narmada basin. Dr.Gangopadhyay is saying that this erectus population in India evolved into modern humans. A rival and mainstream theory is that erectus populations in Africa evolved into modern humans.

The problem here is the nature of the data. The fossil record of erectus in India is sparse, only one confirmed specimen from the Narmada basin. The tool record however does indicate the presence of Homo erectus as early as about 1.2 million years ago. ,That along with the genetic profiles of modern Indians, only inform us of the presence of the two species in a particular location, but not whether one species evolved in to the other. But data informing us of where modern humans originated does exist. A comparison of mitochondrial DNA from populations all over the world has revealed that African populations are genetically the most variable and that this genetic variability decreases in populations further away from Africa. This strongly implies that modern humans originated in Africa and were resident there for a long enough time to evolve substantial genetic variability. They then migrated out of Africa in small groups. Current fossil and genetic evidence suggests around 50,000 to 70,000 years ago. In these small migrating populations genetic variability can be reduced when versions of genes are lost due to random genetic drift. The Indian continent was a recipient of one of the earliest such migrations. The M haplogroup then evolved over a period of time in the populations of the Indian subcontinent. More sophisticated genetic analysis has recently shown that there may have been later smaller migrations of Homo sapiens from Asia to Africa but that doesn't mean humans originated in India. This genetic data is complimented by a study of variability of skull shapes. The pattern of variability mirrors the genetic data, i.e. more variability of skull shape in Africa and then diminishing variability away from Africa. There are other pieces of evidence in support of the African origin of humans. The earliest fossils (about 150,000 years old) of anatomically modern humans are found in Africa. Then there is the earliest evidence of ornamentation, small shells crafted into beads (80,000 years old) implying modern human behaviour. The totality of evidence support an African origin.

This article encapsulates the sorry state Indian science finds itself in. There is the media. Clueless about the science, not bothering to ask critical questions and too lazy to be doing any background research. And then the spectacle of a senior scientist shooting his mouth off with no regard to the reliability of the evidence in hand. "This is indeed an important discovery for the organisation and the research would be taken up further," mentioned the deputy director of ANSI, Nagpur, Dr M B Sharma. The latest incarnation of "India is the fountainhead" of every possible human achievement, in this case genesis itself.

Wednesday, August 8, 2007

The Universal Umbrella

There has been a flood of articles on a report “The Limits of Organic Life in Planetary Systems,” published by the National Research Council of the National Academies of Sciences and posted on the NAS web site. It suggests that life elsewhere in the universe may be quite different than life on earth and that our search parameters should be expanded to accommodate this possibility.

The Times of India carried a column on July 12 2007 by Mukul Sharma. In his column Mr Sharma stresses how diverse life on earth is, a point which is undisputed and uncontroversial but then suggests that

"life on this planet itself has turned out to be so staggeringly diverse and bizarre that to lump it all under one universally descriptive umbrella is beginning to make very little sense now".

I feel this is a case where a columnist having read the press release about alien life got real excited and decided to conjure up some aliens on planet earth. Statements like these serve no purpose except to impress the uninitiated public into believing that scientists have been in the dark all along about all this diversity on earth and don't know what to do with it. What on earth does he mean by one universally descriptive umbrella? I suspect he means a way to organize life in one inclusive classification framework. Mr Sharma is saying that some forms of life are so different that they cannot be included in the classification framework biologists use today. To make his case he describes extremophiles, varieties of bacteria which live in extreme conditions and other organisms that don't use oxygen but chemicals like hydrogen sulphide to power their lives. In stressing how different extremophiles are, he ignores the fact that all life including the extremophiles is united by fundamental molecular similarities. All life has a DNA based genetic system and a nearly identical genetic code, the instructions to translate information stored in DNA into proteins via RNA intermediates. This is taken as compelling evidence that all life forms arose from a common ancestor. The reason for so much diversity? Evolution. Lumping all life in one universally descriptive umbrella is not that senseless. Biologists classify life forms based on their evolutionary relatedness, a method that make a lot of sense, since it is giving us an increasingly clear picture of just how life forms are related to each other and how they diversified. The universal umbrella is not an arbitrary and increasingly unwieldy creation of scientists to pigeon-hole life forms into. The umbrella emerges due to the fact that all life forms on earth are related through common ancestry. As molecular genetic data pours in, science is slowly revealing the one true tree of life, the universal umbrella. If at some point we have clear evidence that some life form on earth is using a radically different molecular system, perhaps one that does not use DNA or one which utilizes a different genetic code, we will need another umbrella to lump those life forms under. Until then, one universal umbrella to describe all life, even bizarre extremophiles, is sufficient.

Which brings me to the second point regarding alien life. I am not an expert on biochemistry and so I cannot judge how realistic are assessments that life using a silicon based chemistry or one that uses ammonia or methane as a solvent instead of water may be possible. The sentence in the press release of the original report and quoted without question by Mr. Sharma that caught my attention was the one which suggested that fundamental requirements for life as we know it may not require " a molecular system capable of evolution and the ability to exchange energy with the environment". Life without evolution? Scientist may disagree on the chemical makeup of alien life but surely they agree that life anywhere will have the properties of replication and hereditary variation. Evolutionary change is a natural consequence of these properties. Without evolution life will come to a dead-end, literally. Required also is exchange of energy. How can chemical reactions be sustained indefinitely without an input of energy? Maybe the full report which I have no access to says something about this. But most science lovers will read only the press report. I hope the people who wrote this report will clarify these astonishing statements.

Three Common Ancestors

Amphibians, especially frogs are being increasingly considered the "canary in the coalmine" of global warming. They seem to be very sensitive to minor variations in temperature and many populations are succumbing to fungal and parasite infections brought about by increased temperatures. Many species may be on the brink of extinction. A new study has shown that although amphibians may be among the first organisms prone to collapse in times of an environmental crises, they are also champions of recovery, rapidly diversifying and filling ecological niches post environmental trauma. An analysis which reconstructed amphibian family trees using a comparison of genes from 171 species show that amphibians diversified very rapidly soon after two of the biggest mass extinction of the Phanerozoic, the late Permian and the late Cretaceous. This is where the problems in the press report crept in.

In summing up the late Permian crises the press report says

"The work revealed that today’s amphibians have three common ancestors, which arose around 350 million years ago. That trio suddenly branched out between 250 million and 225 million years ago – around the time of a global mass extinction at the end of the Permian Period, when some 95 percent of all life forms had disappeared from the face of the planet".

Three common ancestors. I can almost hear biologists grinding their teeth and sharpening their knives at this careless use of the term common ancestor. Amphibians are a diverse group but they also share deep similarities, which have convinced biologists that all amphibians arose from just one common ancestor, i.e. just one ancestral species. Organisms with properties of amphibians originated just once in the history of life. What could the term 3 common ancestors mean? It certainly could not mean that amphibians arose independently on three separate occasions. The probability that three different ancestral species evolving identical amphibian features is vanishingly small. I think what the reporter meant was that about 350 million years ago an ancestral species split into two species, one of which founded the lineage that lead to amphibians, the other founded the amniotes (reptiles, birds, mammals). By 250 million years ago the amphibians had diversified into three main groups ( three orders of class amphibia). After the Permian extinction, the surviving species of these three orders diversified rapidly and eventually gave rise to frogs and toads, salamanders, and caecilians respectively.

Later speaking of the late Cretaceous extinction the report says

"In total, approximately 86 percent of frog species alive today, and more than 81 percent of salamander species descend from just five amphibian species that survived this mass extinction 65 million years ago".

Again, a very careless use of terminology which renders the sentence meaningless. There is no way biologists can acertain using a family tree reconstructed using genetic data that only 5 species survived the Cretaceous extinction. I searched out the original paper and this is what it said

"Approximately 86% of modern frog species and >81% of salamander species descended from only five ancestral lineages that produced major radiations in the late Cretaceous and early Tertiary".

5 ancestral Lineages not 5 surviving species. What this means is that several amphibian lineages (group composed of species related by descent from a common ancestor) survived the late Cretaceous mass extinction. Out of the surviving lineages, 5 were particularly successful.

From original paper to press release, this mutation in term lead to a very different reading of the evolutionary story.

Tuesday, August 7, 2007

The 10 Percent Brain

I could not resist commenting on this one. An editorial in the Times of India (Sept. 16 2005) discussed some new findings of genes related to brain functions and the possibility that the timing of their spread in human populations coincided with the explosion of art and more recently the invention of agriculture. This research by Bruce Lahn, a geneticist at the University of Chicago, has proven to be controversial with other geneticists unable to reproduce his results. As they say, more data is needed...

But that is not what caught my eye in this article. It was this:

"What we do know is that so far, we only use one-tenth of our brain in conscious thought. In time, will we be able to harness the brainpower of the nine-tenths of our consciousness that is dormant? "

Suckers!! Falling for the one of the most enduring urban myths of all. This line is a standard way in which psychics and people who dabble in the paranormal fool their clients into tapping the undiscovered 90% of their abilities! Evolution has no foresight. Evolution does not invest in the future. The brain is an expensive organ to maintain and utilizes a large supply of the body's energy resources. It is unlikely that a brain that is 90% useless or dormant would ever develop. In brain scans it is seen that around 5% - 10% of neurons are firing during any one specific function. Which is probably how the 10% figure made it in popular imagination. However, during the course of the day, different tasks consume the functionality of the entire brain. If 100% of our neurons fired simultaneously, we would not become any smarter, but instead suffer an epileptic seizure. So next time you see an ad by a quack or Reike master promising to take you to a place no one has gone before, don't reach for the checkbook.

More Hot Air From the Press

Here is an example of the kind of science reporting that drives me nuts. The Times of India, one of the leading national dailies had this headline (link not available) on Jan 29 2005; "Temperatures to rise 11° C world-wide". The report described the results of a global warming modeling experiment. The apocalyptic headline was nothing but sensational and did not in any way represent accurately how modeling results should actually be interpreted. Modeling predictions are very sensitive to assumptions made about starting parameters such as how water-vapor, clouds, particles, CO2 actually affects temperature. A combination of worse case assumptions of all these parameters predicts a very high temperature increase while more optimistic assumptions of the starting parameters predict lower temperature increases. According to the chief scientist Dr. Stainforth the high-end increase of 11° C predicted by the model was due to an assumption that the CO2 levels were doubled all at once in the atmosphere rather than over decades and also due to a very simple representation of the interaction of the atmosphere and oceans which act as an important sink for CO2. These critical assumptions were not reported in the article, leaving readers with an impression that a huge increase in temperature in highly likely even if CO2 levels are doubled gradually. Even the most pessimistic climate experts will admit that a catastrophic rise of 11° C is extremely unlikely under any realistic scenario.

Global warming is a real and important phenomenon that is likely to have serious consequences for living conditions on earth. This is all the more reason that the science behind it is reported accurately, objectively and without dramatics so that the public can participate in an informed debate about how to minimize the damage.

Monday, August 6, 2007

The Double Helix

I’m sorry sir, but you’re application for medical insurance has been rejected, since your genetic profile suggests a high chance of contracting Huntington’s disease by 2030. I made up this scary story, but the discovery that made this scenario conceivable occurred in early 1953 when James Watson and Francis Crick discovered the structure of DNA. Noel Lobo wrote an excellent article in the Times of India (May 24 2003) on the 50th anniversary of this event. The story of the discovery of DNA has become part of science legend. The best account of the events is James Watson’s Double Helix. I recommend Francis Crick’s What Mad Pursuit for events and details of Crick’s career post double helix. Media reporting on science tends to be on the dramatic side, far too often over-hyping the significance of a piece of research. But Watson and Crick’s double helix moment deserves all the hyperbole one can lavish upon them.

Absolutely great! But what lessons for Indian science? Why have our research institutions and universities not produced science that is talked about by peers and public alike? For the last several years I have been scanning science news portals on a daily basis and there have been few if any press releases about an important piece of research conducted by Indian scientists working in an Indian institution. Is it because all the bright minds have fled abroad, or maybe Indians are just not good at pure science. I don’t believe either of these theories. It would be instructive to imagine what would have happened if Watson and Crick had showed up to work not at Cavendish Lab’s in Cambridge but at an Indian research institution. Would they have succeeded? The answer I feel is a depressing no. Not because of a lack of funds or instruments but because the Indian institutional system would have either turned them into “career scientists” or forced them to quit. Think of the events that lead to the discovery. Two brash, some would say arrogant loudmouths expressed a desire to solve a problem in an area in which they had no expertise. An Indian lab would have immediately told them to tone down their enthusiasm, to “find their place” in the natural hierarchy and to work on the problem assigned to them. In contrast, Cavendish Lab gave them a separate room so that they could talk without being disturbed. By their own account Watson and Crick stumbled and bumbled towards their objective. Crick twice flooded the corridor outside the lab director Sir Lawrence Bragg’s office because he forgot to secure his suction pump; and Watson knew so little chemistry that he once used a Bunsen burner to warm some inflammable benzene. This would have caused an institutional meltdown in India even possible expulsion. At Cavendish, Bragg told them to stop working on DNA but changed his mind once he realized that there was no stopping them. That they had ignored his orders not to work on DNA was not taken as a personal insult but an indication that these bright young researchers really believed they were on to something big. There was no attempt at Cavendish to interfere with their work. Colleagues generously gave them expert advice, with no expectation to be included in the final paper, their boss never demanded that they take his permission for every little experiment or expense.

The high-energy free intellectual climate spurred them on until the day of the revelation. This scenario is unimaginable here in the bureaucratic Indian institutions, with its obsession for conformity, its contrived and exaggerated respect for seniority and its political interference in research. All these factors contribute to a lack of motivation and commitment and stifles creativity among the scientific staff of these institutes. I talk quite often to friends and colleagues who are now faculty and scientists at various research labs and universities all over India. Yes, the grant money has increased, there is new instrumentation and infrastructure but this problem of a politics ridden, inertia-bound research atmosphere remains. Until that change occurs we will keep awaiting our own Watson and Crick moment.

Saturday, August 4, 2007

Fairplay in Monkeys

Nicholas Wade of the New York Times is a science writer I have always admired. He wrote this article on the sense of fairness ( NY Times Sept.18 2003) which we think is unique to humans. Mr. Wade describes an experiment done with capuchin monkeys in which the monkeys are taught to trade pebbles for food. The monkeys are placed so that they can see each other. Two food items are traded, a less favored cucumber and the much desired grape. If a capuchin gets a cucumber but sees his companion being handed a grape the monkey throws a fit. The behavior suggest that monkeys have evolved a sense of fair play, something which may be an essential attribute for living in social groups. It is a most interesting piece of research and also well reported.

To summarize Mr. Wade writes

"Selfishness might seem the best way for an individual to get the most genes into the next generation, evolution's only coin of success. But biologists have come to understand how cooperative behavior, under certain definable conditions, can have a greater genetic payoff and therefore how genes that foster such behavior could be favored by evolution"

This point needs clarification since biology has seen a bitter debate about selfish genes and genetic determinism. The way Mr. Wade put it seems to imply that selfish behavior exhibited by an individual is the more successful strategy in animals and co-operation can evolve only under certain conditions. But I doubt if there is any data to suggest that any one of these behaviors is more common than the other in social animals. An individual may show kindness and generosity towards kin and be a selfish brute to strangers. In fact I would guess that co-operation at least within kin is more common. The term “selfishness” in his article really reflects the metaphorical motives of genes and not the real motives of individuals. These are not necessarily the same motives. Both selfish and co-operative behaviors are contingent strategies which have evolved in certain circumstances such as living in highly social groups. Which one is employed depends upon an unconscious cost-benefit analysis of the greatest chance of reproductive success. The ultimate causation of both these behaviors is the gene's metaphorical selfish motive in getting the most copies of itself into the next generation. Thus ‘selfish genes’ (ultimate level) don't automatically produce selfish behavior (proximate level).

This clarification of the meaning of “Selfishness” is crucial since one of the biggest misapprehensions about evolution is that if genes have selfish motives then individuals will always behave selfishly with the obvious distasteful implications for human behavior. This need not be so since "selfishness" is the genes metaphorical motive which can lead to a wide range of behaviors ranging from selfishness to altruism in individuals.

Persian in my Genes

This article on the innate nature of language appeared in the Education Times Pune section of Times of India on Sept 23, 2003 (no link available). It is a good example of how the "genes for something" concept is carried to extreme lengths. It 's written by Mr. Sumit Paul, a linguist who occasionally writes columns on language in the Pune Section of the Times of India. In this article Mr. Paul tells a story of a child of Persian descent but adopted by English parents who suddenly acquired an urge to study Persian. This to Mr. Paul was proof that language is in the genes and that adopted children brought up far from their ancestral land may not only grow up with a desire to speak their ancestral tongue but may actually inherit the accent of their biological parents language even if they have had no contact with their biological parents.

Wow! I am sure Mr. Sumit Paul must have listened real hard to hear that "faint" Bengali accent in a child who grew up far away from its Bengali parents ‘cause I sure have not heard a trace of any Maharashtrian accent from my cousins and nephews growing up in California. Language is innate in the sense that a baby has a genetically determined innate ability to learn to speak a language. The ability to speak in any particular language or accent is not innate that is there is no genetically wired circuitry in your brain for speaking in a particular language or accent which is passed down from parent to child, but instead depends entirely on which language and accent a child hears when he or she is growing up. That means that Marathi speaking parents from Pune do not pass on genes for speaking Marathi in a Puneri accent, but just genes for abilities to learn language. Stories like the one about the English child opting to learn Persian and Urdu without ever knowing about his Muslim mother prove nothing. The child in England did not grow up miraculously speaking Urdu or English with an Urdu accent, he had just chosen to study Urdu. He could not have inherited his mother’s language but there is a good chance he inherited her looks. A child with dark hair and dark skin may be treated differently by his white peers while growing up, thus inducing a desire in the child to learn about his roots. Or, it could have been something as trivial as enjoying mutton biryani in a restaurant and then deciding that he wanted to understand this particular culture. Why does a white Australian with no Indian parentage choose to learn Sanskrit? There are hundreds of random unplanned influences from the environment that can determine such choices.

A language prevalent in particular communities may, according to the article, "percolate down to the next generation with remnants of their pristine character” which presumably means an accent. The reason for this is that people have a tendency to marry within their community and therefore their children grow up listening to their parents and neighbor’s accents and not because genes for speaking in a particular accent are being passed down. Stories of a faint accent of the biological parent’s mother-tongue in adopted children brought up in a different environment are usually myths perpetuated by hope and a feel-good factor of the continuity of one’s linguistic heritage. That language is a serious matter for people is evident in sentences like "a language is not only an individual's part of existence, it’s his whole consciousness embedded in his physiological and psychological roots". What exactly this means and how it explains accents being passed down generations is anybody's guess! When the circumstances of these cases are closely examined they reveal some environmental influence which was not taken into account. Ruskin Bond and Tom Alter speak English with an Indian accent with no trace of any British accent but BBC anchors Nisha Pillai and Geeta Gurumurthy speak with a British accent without any Indian accent however faint! Language may be in one's genes but an accent is surely not.

The Loveless Inuit

In their article Voiceless Requiem (Times of India, June 10 2003), Jug Suraiya and Vikas Singh write about language, its importance to humanity and the sad decline and eventual disappearance of hundred’s of languages. They then go overboard and claim that language is so embedded in the human experience that it creates the reality that we see around us. They subscribe to the extreme form of linguistic determinism. This version claims that for example cultures that lack words for certain colors cannot perceive those colors. Or that Hopi Indians don't think of time as past , present and future a conclusion based on the apparent lack of words to describe time. Both these and many of such extremes claims have been shown to be patently false. But Suraiya and Singh seem to have overlooked the literature of false claims. They begin by falling hook line and sinker for the Great Eskimo Vocabulary Hoax which is that Inuit have tens of different words for snow. Urban legend had earlier inflated the number of Inuit words for snow to 200 plus. Current Inuit language dictionaries and linguists have brought it down to a more modest 2! The number 11 quoted in the article is a generous count for snow and snow related phenomenon, not much different than English expressions for the same.

Not satisfied with burdening the Inuit with a vast vocabulary for snow, Suraiya and Singh then claim that the Inuit language does not have words for romantic love. Apparently living in strongly bonded communities precludes the need for Inuit’s developing special attachments to other single members of the tribe. This is an absurd idea, but I followed it up and emailed a linguist expert on Inuit languages. After he had stopped laughing he emailed me a list of words for romantic love in Inuit dialects. Here are some examples, “piqpagigikpi¤” in Inupiaq Eskimo, North Slope dialect, kenkamken in Yup'ik Eskimo of Southwest Alaska, asavakkit in West Greenlandic all of which mean “I love you”!

Humans all over express an identical range of personal emotions and needs regardless of whether they live relatively solitary lives or part of strong communities. Even if the Inuit didn’t have a word for romantic love, one cannot automatically conclude that they don’t form special attachments. This myth i.e., since people speak differently, they must also be thinking differently, has been discredited by linguists and cognitive psychologists. Apart from formal research, one just has to glance at Inuit language novels or movies depicting lust, love, greed, jealousy and revenge to realize that the Inuit develop over their lifetime a range of intense personal relationships with other single tribal members, no different than humans living elsewhere. And yes, they have words to express all of them in their rich language.

Trunk-Less Tree of Life

No story of origins has captivated and excited humans more than the evolutionary origins of humankind. The recent discovery of a 6-7 m.y old hominin fossil nicknamed Toumai, from Chad Africa has added to this excitement. The recent editorial, titled Tree of Life in the Times of India, 16 July 2002, does a fair job describing the discovery but also exposes some basic misconceptions about the nature of evolution. I’ve listed some of the misconceptions below.-

…“could help link the huge evolutionary gap between the 10 million-year-old ape age and the five million-year-old find, believed to be evidence of the first hominids”.

This would mean the huge gap in the fossil record of African apes between 10 million and about 5 million years ago. There is off course no “evolutionary gap” between 10 my and 5 my ago. Apes continued to evolve.

…”the new-found skull, Sahelanthropus tchadensis, is thought to represent that point on the evolutionary time-scale when hominids took shape, moving away from being chimps but still a long way off from today’s humans”.

Humans and chimps shared a common ancestor 7 million years ago. Chimpanzees did not exist 6 million years ago. This early hominin fossil shows enough distinct morphological traits that suggest that it represents the lineage that lead to humans and not the lineage that lead to modern chimpanzees.

…”We need to find our way through these various branches (of evolution) which have their own distinct characteristics, but which are ultimately connected to the main trunk — Homo sapiens”.

This to me represents a deep misunderstanding of the evolutionary process. The article rightly points out that evolution is more like a branching tree than a simple ladder like succession of species, but then it has taken the tree analogy too far by suggesting that different branches of hominins are ultimately connected to the main trunk – that of Homo sapiens. The tree of life however has no main trunk; in fact it has no trunk at all. The analogy of evolution with a tree is useful in the sense that it helps us conceptualize evolution as a branching process, where branches or species once sprung go their own way never to join together again. The concept of trunk is meaningless in evolution since there is no one main ancestor-descendent series in a branching evolutionary tree from which all other branches or species originate. Trunk is a retrospective label assigned to a particular ancestor-descendant series out of the many that may exist that we wish to highlight. The trunk metaphor is also suggestive of a belief in a ladder like progression of species, that a smooth tracing of ancestor and successive descendents in a chosen lineage defines the central inevitable pathway of progress in an evolutionary tree.

Ironically, this view of life describes the story of human evolution particularly poorly. The fossil record of Homo erectus (our immediate ancestor) indicates that populations of erectus were present over a vast area ranging from Africa to Europe to S. E Asia. These isolated populations of erectus diverged and evolved through independent ancestor-descendent successions in these various areas. We recognize some of these descendents by names such as the Neanderthals in Europe and W. Asia , Homo florensis in S.E Asia, while in others areas over Asia they are simply referred to as Homo erectus. Modern humans evolved from one such population of Homo erectus somewhere in East Africa. Scientists put the origin of the hominin lineage at around 5-7 million years ago of which the recent find is an early representative. Our species i.e. modern Homo sapiens appeared around 150,000 years ago. In between these two events several hominin species originated, prospered and went extinct. Our own species co-habited the planet with at least one other – perhaps more- hominin species. This evolutionary story brings to mind not a central trunk sprouting side branches of humanity and reaching its pinnacle in our origin but more a story of populations dispersed by migration seeding new lineages at places they settled, one of which led to us. Thus there was nothing inevitable about our origin. The feeling of uniqueness is an artifact of extinction; our evolutionary cousins are dead while we still live. This makes it seem as if evolution inevitably led to us. Such retrospective coronation is however faulty and one just has to look at lineages which are rich in living species to realize this. How for example from the profusion of modern species of beetles or flowering plants or rats will one identify one main ancestor-descendent succession or trunk? You can only describe these evolutionary trees as having many branches with many living representatives. Hominin evolution similarly did not consist of only one clear pathway, but many complex diverging ones.

The hominid Toumai, as has been rightly pointed out will re-energize the study of human evolution. However, it will not, contrary to what many have suggested, fundamentally change our views about how evolution works or change the basic story of humankind’s origins. The human evolution story, painstakingly pieced together from an impressive array of hominin fossils from Africa, Europe and Asia will also remain fundamentally unchanged. Toumai in fact, lends solid support to the most basic tenet of that story, which is our ancestors originated in Africa. It also gives a poke in the eye to evolution doubters who keep whining “show me the intermediates”, for here is a fossil with an impressive mix of primitive and derived features. Hopefully more fossils from that crucial time period of 5-7 m.y will be found in the near future. Those along with Toumai will help us better understand the details of our early evolution.