Simon Conway Morris On The Burgess Shale

Don't miss listening to Prof. Simon Conway Morris on the Burgess Shale fauna on Paleocast hosted by Dave Marshall. The Burgess Shale is an important Middle Cambrian deposit in the British Columbia Rocky Mountains. It is a Lagerstatte, i.e. it contains exceptionally well preserved fossils and therefore gives us rich details about the animal life and biodiversity of the early Paleozoic oceans and some insights into the geologically rapid diversification of early metazoans. (the Cambrian "explosion").

Why is preservation so exquisite in the Burgess Shale? Reconstructions of the sedimentary basin indicate that the mud that became the Burgess Shale was deposited at the base of a high relief limestone reef which essentially formed a sort of an underwater sea cliff.  Periodic turbidity currents swept in fauna living in shallower  areas and buried them rapidly in the deeper  water at the base of the cliff. These currents form deposits a few cm thick, encasing animal remains a few mm in dimensions. The waters were oxygen starved, thus there was less aerobic bacterial degradation of soft tissue. Add to that were some peculiar geochemical conditions of the Cambrian ocean. One was a paucity of sulphate which retarded degradation by sulphate reducing bacteria. The other, as some recent work by Robert Gaines and colleagues suggest, was the high calcium carbonate saturation levels of the ocean, which lead to rapid cementation of the sea floor in between episodes of turbidity flows.

The image on the left shows CaCO3 cement rich layers in the Burgess shale (source: Gaines et al 2012). These cemented crusts on the sea floor formed an impermeable barrier and reduced the influx of sulphate and oxygen bearing sea water in to the sediment, further slowing down microbial activity. How do we know there was less activity of sulphate reducing bacteria? The researchers analyzed the patterns of sulphur isotopes in the fossil rich turbidity layers and the background sediment.  Sulphate reducing bacteria preferentially take up the lighter isotope of sulphur from sea water. Thus, background deposits with normal or enhanced microbial activity have a lighter isotope signature relative to the Cambrian sea water standard. On the other  hand, less microbial  activity means  less fractionation of the lighter isotope into bacteria and ultimately into the sediment matrix. In Burgess Shale type deposits the fossil rich turbidity layers capped by CaCO3 cements show an enriched or heavier sulphur isotope signal indicating less microbial activity. Finally, since the bottom  waters were anoxic, there was little benthic fauna living there. This meant that the cement crusts were not disturbed and broken by bioturbation and remained effective seals throughout the crucial first few weeks of burial when degradation is at its peak. Soft tissue does break down due to slowed microbial activity and fermentation and methanogenesis. The three dimensional carcass collapses into a nearly two dimensional carbon rich film. The final result is that recalcitrant extracellular organic material like cuticles, chaetae, and jaws are preserved as compressed thin carbonaceous films often just a few microns thick, the soft fine grained mud encasing the carcass helping preserve fine morphological details. This preservation style also meant that some animals lacking recalcitrant tissues like flatworms, mesozoans, nemerteans and unshelled molluscs are less well represented in the Burgess Shale style deposits ( Butterfield 2003). Peculiar preservational styles by their very exceptional and localized nature impose a bias on the fossil record that palaeontologists must recognize to understand true evolutionary patterns.

The examples on the left shows Burgess Shale style preservation of Arthropod (B), Polychaetae worm (C) and Arthropod (D) [source: Gaines 2014]. This style of preservation actually appears first in the early Neo-Proterozoic  and then disappears for about 150 million years until the earliest Cambrian. It again declines by late Cambrian with the earliest Ordovician being the last recorded example of this taphonomic style. A unique combination of geological conditions and early diagenesis of sediment prevailing in the latest Proteozoic and earliest Cambrian resulted in these fossil deposits. This time period also has other forms of detailed preservation of soft tissues, the two most important being the Edicaran style preservation wherein the remains of macroscopic plants and animals deposited in sandy and silty sediment were draped by microbial mats and compressed to form impressions (death masks) on the sediment surface. The other important style is the Doushantuo style preservation (named after the Doushantuo fossil beds of late NeoProterozoic age, China, containing preserved algae and putative embryos and larval stages of early animals ) where phosphate minerals are attracted to and precipitate around organic tissue preserving delicate cell outlines and internal organs. Very occasionally, the same fossil will show two different preservational styles, for example, the extracellular tissue preserved in the Burgess Shale style while  internal organs preserved in the Doushantuo style. These taphonomic "windows", as they are referred to, appear and disappear through the Neo-Proterozoic to Cambrian period. For example, the Edicaran style preservation first appears in the late NeoProterozic around 580 million years ago or so. Considering that microbial mats which play an important role in this style of  preservation are pervasive through the late Archaean and the Proterozoic, the first appearance of the Edicaran remains is then likely an evolutionary signal of the first appearance of  macroscopic multicellular  eucaryotes on earth. The disappearance of Edicaran style by the earliest Cambrian also suggests a biological feedback. The evolution of macroscopic benthic animals burrowing and grazing on bacterial mats may have destroyed the cover protecting the faunal remains. Preservational styles are controlled not just by geological conditions but due to contemporaneous evolutionary innovations too.

Coming back to the talk! Prof Simon Conway Morris describes the history of research on the Burgess Shale,  how he got into researching it, details of some of the animals found in it including the famous Pikaia. This has been interpreted as an early representative of  the chordates from which the vertebrates evolved. Overall, Conway Morris gives a masterly authoritative talk.

I would have loved to hear him talk a little more about the broader questions that arise from this deposit. Are the origins of the Burgess animals to be found in the earlier Edicaran fauna? Does the Cambrian have greater morphological disparity than later periods in earth history? Has life followed a contingent unique pathway or does examples of convergence tell us something deeper about the general principles of evolution? ..or an intelligence which frames the ultimate laws and guides evolutionary processes. Simon Conway Morris has indicated elsewhere his thoughts that the Universe is the product of a rational mind and that evolution is but a search engine and I wish Dave Marshall had pressed him on his theist beliefs. But I guess the topic was the fauna of the Burgess Shale and in particular that iconic quarry in British Colombia.

He did mention in passing something which I think  is an important aspect of this story. Just as he had finished his Master's degree from Bristol University in 1972, a project headed by Prof. Harry Whittington on the Burgess Shale was starting at Cambridge. Simon Conway Morris saw this as a good opportunity. At around the same time, the Chicago school of palaeontologists lead by David Raup (who died last week), Jack Sepkoski and Tom Schopf had started a program to broaden the scope of palaeontology to include rigorous quantitative methods on large sample sets to understand biodiversity and patterns of evolution, bringing the field of palaeontology, as John Maynard Smith famously said, to the "high table of evolutionary theory". These events underscore the important point that for all your brilliance in something, circumstances and timing matter. Simon Conway Morris was present at the right time at the right place. And he did the Burgess Shale fauna justice.

Some Interesting Podcast's I've Listened To Recently

I should be sharing this list more often-

1) On America's other migrant farm workers - Bees! Biologist Laurence Packer talks about the importance of bees in American agriculture. Incredible- millions of them are transported by trucks to aid in pollinating almonds and other fruit crops from one end of the U.S to the other!

2) Science Friday- Summer Book List 2014- What is not to like about a conversation that discusses a book like Proof- The Science of Booze!... and many more books featured in this talk.

3) Science Friday- Crafting Perfect Beer- more on the microbiology of beer and the burgeoning craft beer industry in the U.S.

4) Planet Money- The History of Light: Before there was the light bulb there was fat! Planet Money is one of my favorite podcast; it is economics explained with a light touch. This episode features how we got from candles made from cow fat and whale blubber to light at the flick of the switch and its economic implications in terms of the massive increase in human work productivity.

5) On Point Radio- The End of Night: A nostalgic look at what we have lost with our city life- the end of the night sky. Wonderful remembrances by callers too.

6) Fresh Air: To End All Wars: Its the 100th anniversary of the beginning of the Great War (World War I) and author Adam Hochschild discusses his book To End All Wars- you read this with a shudder- " I think the war remade the world for the worse in every conceivable way: It ignited the Russian Revolution, it laid the ground for Nazism and it made World War II almost certain. It's pretty hard to imagine the second world war without the first."

Conversation With An Ex Geological Survey Of India Geologist

This is the first of what is hopefully a series of posts with my Pune based geology friends. Indian scientists don't talk enough with the public. We see them only on "Science Day" at various institutions or at major events like satellite launches, nuclear protests and earthquakes. But a more frequent conversation with the public conveying the joys and challenges of a science career is missing. Most scientists don't make momentous discoveries. They spend their careers framing smaller manageable questions and attempt to find answers for them. This process of science and small victories is revealing and inspiring too. So these "conversations over coffee" posts are an attempt to highlight the work of my geology colleagues and friends presented in a more informal casual form and made more accessible via social media.

In this conversation I talk with Dr. Sudha Vaddadi (above left having a coffee with me "The Fractured Geologist") who after a two decade distinguished career with the Geological Survey of India (GSI) is now visiting faculty at Fergusson College, Pune. We talk about her PhD research, mapping the complex Deccan lava flows, lack of direct recruitment in the GSI and resulting career stagnation, teaching stratigraphy and the need for more quantitative methods in Master's degree programs, working as the only woman in the GSI office, and waiting long hours in the field  for bullocks to pull a broken down jeep to the nearest garage.

Our conversation and email question and answers took place from late January through the month of February. The only changes I have made to the email interview document is to add a few hyperlinks.

[modified on March 5th- changed the order of the questions, brought the question about GSI recruitment to the top]

When California Was An Island And Other Stories

Economist Tim Harford is hosting a fun podcast series on BBC Pop-Up Ideas. There are 3 episodes on maps which make great listening:

1) Tim Harford- The Power of Maps

2) Jerry Brotton - Mapping History  He is the author of the book A History Of The World In 12 Maps which is definitely of my reading list.

3) Simon Garfield- Maps And Mistakes.. which tells us the story of how in the late 1600's California became an island on the maps of the day..

Very fun to listen to..

Confused Article In The Hindu On Evolution, Disease And Paleolithic Lifestyles

What's up with The Hindu?.. another terrible article on science and evolution and biology by a medical professional soon after the recent ignorant hateful essay on homosexuality. Following reader outrage and detailed corrections that article on homosexuality has been retracted by The Hindu.

This one is by a cardiologist Dr Hegde. He begins thus:

Darwinian evolution has become outdated and its place is taken by the Lamarckian hypothesis of evolution by environmental compulsions. Darwin himself agreed with Lamarck but the neo-Darwinians, who have a big business interest in keeping the status quo, are at it even now. Even Erasmus was for environmental evolution long before Darwin came into the picture. Most of our pathophysiology of diseases is based on the Darwinian model unfortunately and it has to change for good. Earlier the better.

Darwinian evolution dead but kept alive by a conspiracy of big business... What utter rubbish! Later Dr. Hegde complains that "medical doctors do not go into evolutionary biology, even if a few of them go into biology". I hope he has counted himself in that list of medical doctors not getting into evolutionary biology for the above para is as uninformed as it gets.

Lets gets some terminology out of the way.

Science Proceeds By Funerals

Above all, science is a human institution. And as a machine for thinking, it's greater and more powerful than any of its single participants. You said that science proceeds by tiny steps. It also proceeds by funerals.

University departments are just waiting for the professor to get out of the way so the younger guys can get in.

That was author Ian McEwan on a very listenable hour of Science Friday on the importance of science writing in science books as well as science in fiction. The other guests were cosmologists Brian Greene and Lawrence Krauss.

I thought Ian McEwan gave a really good account of why he includes science in his books:

FLATOW: Ian, why do you put science in your books? What - why do we have to know about quantum mechanics? Are you purposely doing that to teach us something or just to...

MCEWAN: No, absolutely not. No.

FLATOW: No.

MCEWAN: It just came along with the character. It's a reflection of my own pleasure in it, but it seems just a human enterprise. I mean, this is - I mean, the standard measure of how alive you are is the measure of your curiosity, and I think of science as organized curiosity.

We once relied on priests to tell us the shape and nature and purpose of the cosmos and life itself. It's been a long, slow story of that undoing. We now have a far more interesting story, and it's also penetrated our lives. I mean, there's climate change, and we all have these intricate, beautiful machines in our hands, and it's impacting on our decisions about bioethics and many other things.

So if we think of the novel as an investigation of the human condition, technology and science is now so woven into that condition. You cannot escape it. So it's inevitable, I think, that...

Download / Transcript

Chinatown And Water Law On Generation Anthropocene

No.. no.. Jack Nicholson didn't show up on Gen. Anthropocene to revisit his great role in the movie Chinatown. In that movie, detective J.J.Gittes played by Nicholson uncovers a shady plan set in the early 1900's  to monopolize the water resources of Owen's Valley and to divert that water to the growing city of Los Angeles.

Buzz Thompson who is an expert in environmental and natural resources law and policy has a personal connection with California's dodgy water history as he recounts how his grandfather's farm was bought over by the city of Los Angeles in the early 1920's using a local farmer as a front and then letting the farm lay fallow as it diverted water for urban use. 

He also gives a tutorial on the different water use doctrines prevalent in the U.S as he explains the differences between the riparian water use doctrine of the eastern part of the U.S. versus the prior appropriation water use doctrine common in the west and also talks about how enforcement of water law has generally failed in the U.S. Another important topic covered is the economics of water use especially in the context of water recycling.

 Excellent conversation from Gen Anthropocene.

Great Conversations: Edward Larson On History Of Evolution

I was going through my podcast collection over the weekend in preparation for a hiking trip to the Himalayas ( more on that later this week!) and found one of the great talks I have heard on evolution. This is Edward J Larson's superb exposition on the history of creationism in the United States and its transformation (or should I say evolution) into the intelligent design movement of recent  years.

Edward J Larson is Professor of History and Law at University of Georgia. His book Evolution: The Remarkable History Of A Scientific Idea is also an excellent summary of the history of the theory of evolution.

But his talk is really worth listening too. Goes straight into my Great Conversations collection.

Geophysicst Mark Zoback On Fracking

Another terrific geology related talk on Generation Anthropocene. Geophysicist and shale gas expert Mark Zoback attempts to clear up the many misconceptions about fracking. He doesn't minimize or take lightly the negative impact of shale gas drilling, but rather puts it in a broader context. The greater risk of contaminating overlying aquifers is not from the act of hydraulic fracturing itself but from improper well construction and from leaky ponds which are constructed to store waste water that flows back out of the formation. This water may contain metals like iron or arsenic flushed by reaction with the shale. So actually according to him, there is nothing in the fracking fluid that is dangerous. But that fluid after reacting with the rock may become toxic.

Shale gas drilling companies don't have to disclose the exact composition of the fracking fluid as they have an exemption under the Clean Water Act. But perception does matter. As Mark Zobeck points out, there was growing support for nuclear power in the U.S. until the accident at Fukushima occurred. Public perception about risk can reverse major energy policy decisions regardless of the actual risk. If that is so, then why slow down or kill the shale gas goose? Perhaps it will be wiser to change policy and to come clean about fracking fluids.

Meanwhile, on the topic of shale gas in India,  a reader wrote in a comment on an earlier post I had written about Indian shale gas prospects:

US geological survey says the total shale gas reserves to be 6.1 Tcf, contrary to 63 Tcf by EIA. What are your views on this?

That is a major downgrade for Indian shale gas prospects. I could only suggest this possibility:

thanks Dakshina.. yeah.. i saw those figures.. hard to say but downward revisions are going on in many other basins around the world.. perhaps the actual recovery rates observed from shale gas wells i.e. their performance over a longer term have not been as good as initially projected..leading to downward revision of technically recoverable resources in other areas as well.. or maybe it has to do with the reassessment of the basic geological data.. can't say for sure without reading more details.. ///

Also worth reading is another article by Mark Zoback on the seismic risk posed by shale gas drilling and waste water disposal.

Mars Rover Scientist John Grotzinger Explains What It Is All About

Science Friday hosted Mars Rover Project Scientist John Grotzinger. He explained with clarity the instruments on board and what the mission is about:

From the transcript:

But from orbit, we could already tell that as we approached this mountain in the middle of Gale Crater that we informally refer to as Mount Sharp, that there's a succession of layers that are five kilometers thick, so that's a bit over three miles. And it's almost three times as deep as the Grand Canyon. And what we learned ever since the time of John Wesley Powell's pioneering trip down the Grand Canyon, staring up at the walls of the canyon and wondering what those layers preserved, I think we're doing the same thing.

We look up at this, and we can only imagine that this represents a tremendous swath through the geologic history of Mars, its early environmental evolution of what might be tens, hundreds, maybe even a billion years, hundreds of millions of years to a billion years. And that interval of time that we're sampling occurred somewhere between three and four billion years ago.

So we're for the first time really probing the next dimension of Mars exploration, which is the dimension of deep time.

Fascinating....Curiosity is not equipped to directly sense any signature of life like microbial respiration. It's all about doing as thorough a job of documenting the mineralogy and geochemistry of the rocks and piecing together a story of the geological evolution of the sampled terrain. In doing so, the hope is to identify habitable environments, a place that had or has water.

Back on earth, life in the Pasadena diner called Conrad's frequented by Mars mission scientists just got a lot busy. From the recent Nature News article :

Grotzinger was a regular at Conrad’s in 2004, before and after his working days on the rover Opportunity, which landed that year along with Spirit, its twin, comprising the Mars Exploration Rover mission. Because the rovers were positioned on opposite sides of Mars, one team would be having breakfast while the other would be eating dinner. “The waitresses were always confused,” he recalls. This time there is only one rover, but still no standard working day. Adapting to ‘Mars time’ requires starting each Earth day 40 minutes later than the last to match Martian daylight, inducing a state of perpetual jet lag.

Also, Mars Rover Curiosity is tweeting. You can follow the mission @MarsCuriosity. What a great way to engage the public in this mission and get them excited about science.

I am the 1,001,964th follower! Looking forward to at least two years of updates from the mobile geology lab on Mars...

Would It Matter Where You Placed The Anthropocene?

I have been listening to an absolutely riveting series of talks hosted at Generation Anthropocene. This is a project dreamed up by young Stanford University researchers and it involves interviewing scientists working on the broad theme of human impact on ecology and environment and consequentially the question of whether there is now a case to be made for defining a new geologic epoch called the Anthropocene.

The answers to where one would place the Holocene-Anthropocene boundary usually converges to either the beginning of Agriculture or the Industrial Revolution because both involve big changes to various aspects of the earth's environment. While these two, especially the Industrial Revolution, came through as a strong candidate, the most thought provoking answer was given by ... well off course .. a geologist... Jon Payne.

He suggested we take a methodological approach and understand how geological boundaries are defined. There has to be a distinctively recognizable sedimentary section which contains evidence of a faunal break i.e. a change in the earth's biota marked by the extinction of some species or the appearance of some new species.  We subdivide geologic time by recognizing that there has been some change in the earth's biota. Looking way back in the earth's past, sedimentary sections containing these transitions cover time periods well beyond the human time scale i.e. the sedimentary layers may represent a time passage of thousands of years.

Sediments usually accumulate in layers quite slowly over time periods longer than the scale of historical events. So, taking a long view, choosing as the beginning of the Anthropocene either the Industrial Revolution or World War II  won't matter, since all these events will collapse as one instance of sediment deposition. A geologist looking back several million years from now won't be able to discriminate events that took place a few tens of years apart.

In my opinion that doesn't make the concept of Anthropocene a useless exercise. For example, the boundary between the Pleistocene and the Holocene is defined by the disappearance of two foraminifera species and is dated as 10,000 BP radiocarbon years. These events mark a passage of few tens of years. Similarly,  today there would be sediment accumulating in a lake or a quiet deep sea that contains very thin layers that mark a sudden rise in a geochemical indicator of the Industrial Revolution or some other human activity.

We may mark that as a beginning of Anthropocene today. These deposits may even get preserved into the geological future. It's just that millions of years from now absolute dating methods like carbon14 that may discriminate events on the order of few tens of years will be useless on these deposits and the error bar on the dates obtained for these rocks will be on the order of hundreds to thousands of years. As a physical entity, the boundary in deep future may be recognizable as a sedimentary layer marking the disappearance of a significant number of species, although correlating that boundary with a specific historical event may not be possible.

Other talks that I liked were by Jon Christensen who talked about the myth of the American Frontier, Rodolfo Dirzo who talked about tropical biodiversity and Doug Bird who spoke about the native Martu peoples of Australia and their history of landscape management.

One refreshing aspect of these talks are that the hosts are all graduate students. What an opportunity to have an extended chat with your intellectual mentors and find inspiration in their work.

And who knows... start thinking of a career in science journalism.

Highly highly recommended.

ExxonMobil Were Playing Both Ways On Global Warming All Along

Fresh Air has an absolutely fascinating interview with journalist Steve Coll who has written a new book on ExxonMobil.

For many years ExxonMobil engaged in a campaign to downplay the human role in global warming and tried to discredit the science of recent climate change.

And yet:

GROSS: Just one more thing about climate change. During the period when ExxonMobil was trying to defeat global warming science, at the same time scientists within Exxon were trying to figure out, well, if the planet is warming, how can we profit from that? So they work in both fronts at the same time.

COLL: Well, that's right. They're a science-based organization. They employ a lot of geologists, and the mission of those geologists is to understand the Earth's structure and how changes in temperatures, geology, technology, could intersect to create opportunities to find oil. And as the book reports, geologists in some of their most important kind of discovery departments were looking at how warming might unlock oil reserves and positioning ExxonMobil with advice about how to think about that.

GROSS: So in other words, Exxon wanted to defeat global science because that says that fossil fuels, burning fossil fuels is warming the climate and creating weather changes and climate change, and that would mean problems for Exxon because it's the fossil fuel industry.

But at the same time, its own scientists were saying, well, it looks like the Earth is warming, so let's see what new oil reserves that might open up to us.

Those new reserves that might open up were under the Arctic sea bed, made more accessible as increased summer melting of the Arctic sea ice makes it easier to explore and eventually exploit those resources.

There are a lot more interesting tidbits in this long interview including ExxonMobil's tussle with the U.S. government over human rights issues in oil rich countries like Chad and the company's increasing interest in unconventional oil and gas resources.

Out Of Siberia - Dogs Not Humans

The endearingly fascinating topic of dog domestication is in the news again. A skull with features that are a mix of wolf and dog was found in the Altai mountains of Siberia. It has been dated to around 33,000 years ago, before the Last Glacial Maximum, a period of intense expansion of polar and mountain ice sheets that began around 26,000 years ago and lasted until around 19,000 years ago.  It may represent an early wolf to dog domestication "in progress", but one that researchers feel was aborted by the advent of the last Glacial Maximum, when human populations in this region dispersed.  There is no evidence in younger deposits from this area of domesticated dogs, despite there being an occasional human presence.

I wrote about this topic some weeks ago and I commented that there probably were many such instances of marginal members of wolf packs getting acculturated to humans and getting self-domesticated or being pushed in that direction by human selection of docile traits. This is after all a meeting between two hyper-social species and contact between wolf and humans would have been a very common occurrence. Another equally old dog skull from a cave in Belgium suggests that there were multiple instances of dog domestication.

What struck me about this latest discovery is the age and the place - 33,000 years ago in the Altai region...... Denisovans??

Modern humans were not the only inhabitants of this region of Siberia.  A  population of another distinct human "species" or variety, descendants of an earlier human migration from Africa about half a million years ago, also lived in this region. Their remains  were found near Denisova cave in the Altai mountains of Siberia and judged to about 41,000 years old.

Its fascinating to speculate on whether there were any instances of wolf domestication in the company of these other human species. The Denisovans  (and the Neanderthals) were human lineages that had a long presence lasting more than one hundred thousand years in Asia and Europe and they would have encountered wolves routinely. We don't know anything about the social and cultural aspects of Denisovan society, but we do know that their cousins the Neanderthals lived in closely knit social groups.

A lot has been said about what the differences may have been between these archaic human groups and "modern" humans. Put forward are differences in cognition (we were just smarter), language and communication skills, division of labor (modern humans had more efficient food gathering strategies),  home range and mobility affecting trade and cooperation with other groups (Neanderthals did not trade as much with other groups). These are all speculative and maybe we can add one more.

These archaic humans did not or were unable to domesticate the wolf. No remains of domestication have been found so far, associated with the Neanderthals. Does the same apply to the Denisovans and other archaic human groups scattered across Africa and Asia?

That off course could be a reflection of something about their behavior as individuals and as a society. Perhaps the wolves themselves stayed away sensing a lack of that bit of empathy, perhaps their hunting methods did not require cooperation with a willing canine partner. If there is evidence for dog domestication or partial domestication about 33,000 years ago, could there be even earlier instances of the dog? And if the timing of dog domestication overlapped with modern human contact with Neanderthals and Denisovans from 45,000 to 30,000 years ago,  did the dog give some advantage to modern humans in eking out a living over these other human "species"?

Testosterone Tattoos And Tequila Equals Snake Bites

Here is a great way to begin the New Year. Start following Quirks & Quarks, a weekly science talk show of the Canadian Broadcasting Corporation hosted by the lively Bob McDonald.

I came across it recently and have heard some pretty interesting talks already. Here is a sample from the last couple of months -

The Dolphin In The Mirror
Pinning Down The Permian Extinction
Out Of Africa And Hybrid Humans
Cosmos And Dark Energy

As for the quirky post title?... Listen to the Show! :)

Have a great 2012..

Some Thoughts On The Evolution Of Dogs

Let me begin though with David W. Anthony's musings about the domestication of horses from his book The Horse The Wheel And Language:

Modern horses are derived from very few original wild males, and many, varied females.

In wild horse society there is a female hierarchy and mares are disposed to follow the lead of a dominant mare. Stallions on the other hand are more independent and react violently when confronted.

...A relatively docile and controllable mare could be found at the bottom of the pecking order in many wild horse bands, but a relatively docile and controllable stallion was an unusual individual - and one that had little hope of reproducing in the wild. Horse domestication might have depended on a lucky coincidence: the appearance of a relatively manageable and docile male in a place where humans could use him as the breeder of a domesticated bloodline.

From the horses perspective, humans were the only way he could get a girl. From the human's perspective, he was the only sire they wanted.

Well said!

Horse domestication depended on active selection of traits by humans from the very start. It may have been different for dogs at least in the earliest stages of human wolf interaction suggests naturalist  Mark Derr in an interview on Fresh Air. 

There are many hypothesis on how wolves got domesticated into dogs.

The puppy hypothesis suggests that abandoned wolf puppies were adopted by humans and then the more sociable and docile amongst them were allowed to breed. This involves selection pressures imposed by humans from the very start.

Then there is the garbage midden hypothesis. Wolves started hanging around human camp rubbish sites.  The key element in this hypothesis is that only wolves who were instinctively docile and perhaps not getting enough food in the wild engaged in this behavior. So there was a self selection for docile traits in the wolves who gradually got used to be near humans.

The third is the hunting band hypothesis. Humans began following wolves on hunts or maybe wolves started following humans on hunts.  These bands of wolves became socialized with humans and  isolated from other bands of wolves. Again it is possible that instinctively docile wolves were more likely to follow human hunts if the reward at the end was food which was hard to obtain otherwise. So there is an element of self selection in this hypothesis as well.

Mark Derr tilts towards this third hypothesis. To me, it hard to pick out the stronger contender. The three hypothesis are not mutually exclusive. The thing is that all three situations would have been a common occurrence. For example its reasonable to imagine a scenario whereby a docile male sifting through the garbage dump gets bold enough to latch on to a female adopted as a puppy and living amongst humans.

The three situations would have overlapped many times. Socialization could have occurred via all these three interactions. After that there would have been more severe direct intervention and selection by humans for traits like docility.

There are other interesting questions about dog domestication. For example, was there just one center of domestication or did domestication take place many times in different places? The Middle East is considered the likely place for dog domestication based on  arguments that the dogs from this region show more genetic variation pointing to a source population of greater antiquity. There also have been a case put forward for China being the place where dogs were first domesticated.

Considering the likelihood of repeated contact between wolves and humans there were probably many independent attempts to domesticate the wolf. Fossils of dogs and wolf-dog hybrids as old as 30 thousand years ago have been discovered from various place in the Middle East, Europe and Siberia suggesting multiple domestication attempts, perhaps successful ones.

What comes to my mind is how incredibly violent the initial process of domestication would have been. Wolf-dog pups and young adults not to the liking of humans in terms of their temperament and behavior and form would have been put to death often by a whack to the head.

As a dog lover I shudder at the thought.

Reassembling Pangaea In The Year 1493

This is the second great talk I have heard on Fresh Air in the past few days. Author of the book 1493: Uncovering the World Columbus Created Charles Mann talks about the impact on the Americas and Europe due to the sudden exchange of humans, animals, plants, parasites between the continents following Christopher Columbus's voyage to the America's in 1492.

He frames this exchange within a larger geological context -

Mr. CHARLES MANN (Author, "1493: Uncovering the New World Columbus Created"): Well, if you think about it, you know, there's been a tendency in textbooks now to kind of downplay Columbus because they say he was a bad guy, and he mistreated Indians, and he discovered the Americas by accident and so forth.

But to ecologists, he was this super-important figure, and the reason is that 200 million years ago, as you remember learning in school, the world was a single, giant land mass they call Pangaea, and geological forces broke it up, creating the continents we know today. And over time, they developed completely different suites of plants and animals.

And what Columbus did was bring the continents back together. He recreated Pangaea, in effect, and as a result, huge numbers and plants and animals from over there came over here, and huge numbers of plants and animals from over here came over there, and there was a tremendous ecological convulsion, the greatest event in the history of life since the death of the dinosaurs.

As an aside.. he is right off course that after the supercontinent Pangaea broke up more than 200 million years ago, different continents had evolved different suites of plants and animals. But Europe, Asia and the America's were not completely isolated from each other from the breakup of Pangaea until the Columbian exchange. From time to time during the early Cenozoic there were faunal exchanges ..mammals especially migrating via the Beringia land bridge (Siberia -Alsaka) to and from between Asia and America and via the Greenland land bridge in the early Cenozoic between Europe and America. These immigrants also must have caused ecological upheavals of their own. They would have been competition for resources and they must have brought over parasites and caused much death and destruction. We have a more guilt free dispassionate view of these faunal turnovers and extinctions. Tim Flannery has the details of these ancient exchanges that took place tens of millions of years ago and the ecological history of the America's in his excellent book The Eternal Frontier.

Charles Mann though weaves many fascinating stories of the Columbian exchange. One that caught my eye was on the impact of malaria on the institution of slavery. The climate which made the southern parts of the America's friendlier to intense plantation agriculture were also environs in which malaria thrived. Africans were more resistant to this newly introduced disease while indentured servants from Britain and Europe who were more commonly hired to work the fields in the earliest days of colonial settlement were dying off in great numbers. It made economic sense to start bringing over more Africans to work on the plantations.

The word exchange means that the movement of people, animals, plants and diseases went both ways. The damage in terms of human deaths, deprivation and societal disruption though was overwhelmingly more in the America's. I have often come across a common impression that it was technology, firepower and political and financial institutions that gave Europeans the decisive advantage over Native Americans. Those did play a role, but the factor that titled events in favor of Europeans was the evolutionary history of peoples, rather resistance or lack thereof to disease. In a strange twist of fate, Europeans benefited from both a lack of resistance to certain diseases as well as from resistance to others. A lack of resistance to malaria stopped newly arriving European poorer classes from being tied to harsh servitude in plantations in the south where malaria was prevalent. Instead resistance to malaria lead Africans into bondage. On the other hand Europeans had evolved immunity against small pox and many infectious diseases contracted from domesticated animals from time to time. Native Americans had not encountered small pox before and not having a history of animal domestication lacked immunity against animal diseases that occasional jumped hosts. They died in their millions leaving vast swathes of countryside unattended and empty for European settlers.

America though had its grotesque revenge via the potato and guano which was used as a fertilizer. Originating in Peru, the two teamed up and initiated intense potato cultivation all across Europe. Ireland especially became addicted to the potato. But the spud carried with it a fungal parasite. In the mid 1800's the potato crop all over Europe failed. More that a million Irish died of starvation partly due to the blight and partly due to Britain's refusal to divert grain to Ireland.

One last fascinating demographic titbit about the role of Africans in building North America:

..And the second thing is that what happened after the Europeans came was not so much that Europeans came, but the Africans came. The number of Africans who came to the Americas up till about 1840, 1850 far outweighed the number of Europeans. There were three Africans for every European who came to the Americas in those first couple hundred years.

GROSS: And this is because of slavery.

Mr. MANN: Because of slavery. And so the Europeans who came, like, you know, many of my ancestors in the later part of the 19th century came to landscapes that had been radically changed, but they had - and to new cities. But those cities had been built (by) African hands, the landscapes had been reworked by African hands, the boats that were going up and down the rivers were piloted by African crews. And so that - there was a tremendous change in the very distribution of the human race on the planet as a result of Columbus.

Globalization has done great things to us as a people, but it has been served up with more than its fair share of pain.

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Vertical Exaggeration Of Relief During World War 1

In Google Earth you can make the landscape look more rugged and dramatic by increasing Vertical Exaggeration i.e. by increasing the vertical scale relative to the horizontal scale of the map.  It is a common technique used to bring out subtleties in topography and to accentuate  relief. 

Perspective plays an important role in our experience of relief. A dropped coin or a small object is easier to find if you lie flat on the floor and bring your eye level as close to the floor as possible. You can get the same effect by using the tilt function in Google Earth.  In his book on World War 1 To End All Wars Adam Hochschild describes one such example of vertical exaggeration or perception of relief experienced by soldiers looking out from their trenches into the open countryside:

From his Fresh Air Interview with Terry Gross -

I also went to some of these battlefields because I always love to see the places where the history that I'm writing about took place, and you learned something there too. One thing that struck me for instance, I went to a place called High Wood because one of the people that I quote in the book is an infantry officer who gives a dramatic description at one point of a very small cavalry detachment when they were having trouble taking the German position. A small cavalry detachment charged up the hill, disappeared over the brow of the hill and then were never seen again.

So I thought could I find this hill? Well, I went looking for it. I found it. What you realize when you're there is that it's not something which I walking around or you walking around today would describe as a hill. It's, you can barely see the slope in the ground and then that makes me realize that all these descriptions you read from the war of capturing hilltops and ridges and crests and so on are written from the point of view of somebody who's lying on the ground trying to stay underneath all those bullets. Just it's a useful reminder when you go to the place

Did the soldiers really perceive those hills to be larger than they were? Their perspective from ground level could have made the relief stand out but there could be a couple of other things going on. Maybe  relief was sharper during the war but in the decades after the war the landscape has been reworked intensely. Soil rearranged by farming, ditches and crevasses filled and the topography really has become mellower. There is also the soldier's psychological perception of the landscape around them. After watching their comrades being mown down in futile charges against German machine gun pickets, for those bone tired shell shocked soldiers the words hill, valley and crossing may have taken  on a more threatening meaning.  A gentle slope might seem steeper than it was, a shallow depression might appear in the mind's eye as a deep valley. When you need to cross them to reach the enemy territory they might appear to be desperately formidable obstacles.. as menacing and impassable as the enemy waiting for you in the trenches.

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Imagination And Art In The Cave Of Forgotten Dreams

Filmmaker Werner Herzog got a once in a lifetime opportunity to enter the Chauvet caves in France which has some exquisitely preserved rock paintings, dated to about 30 thousand years ago. He made a 3D movie of the interior of the cave.

On Fresh Air he talks about his experience:

GROSS: And they wanted you to keep on the walk so that you didn't contaminate the rest of the cave, yeah.

Mr. HERZOG: Oh, you never - can never touch anything. It's not just contaminating. There are footprints, fairly fresh footprints. You do not want to superimpose your print of your hiking boot upon it. There's...

GROSS: Oh, over the cave-bear print. Yeah. 

(Soundbite of laughter) 

Mr. HERZOG: Yes, you just don't do this. And there's a footprint of a child, maybe eight-year-old, this very mysterious. We couldn't film it. We were not allowed, because it was deep in the recess of the cave.

The mysterious thing is that next to this footprint, probably a boy, probably around eight years old, parallel to it runs the footprint of a wolf. And I was very, very puzzled: Did the wolf stalk the boy? Or did they walk together as friends? Or did the wolf leave its footprints 5,000 years later? It's stunning. The lapse of time is completely and utterly stunning.

 
What a context for an artist to let loose his imagination! The Cave of Forgotten Dreams indeed.. but also the Cave of Infinite Imagination.

Werner Herzog also recently joined physicist Lawrence Krauss and author Cormac McCarthy in a conversation about how science and art inspire each other. Speaking about the differences between art and science Krauss remarks:

Science is imagination in a straitjacket.

Not quite so for the artists in the Cave Of Forgotten Dreams.

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Every Pot Of Coffee You Make Is Dinosaur Pee

I wouldn't have come up with a post title that weird...

but I quote from Charles Fishman's interview with Terry Gross on Fresh Air. Mr Fishman is the author of The Big Thirst: The Secret Life and Turbulent Future of Water and he reminds us about the origin, nature and the journey of water on earth -

Mr. FISHMAN: And all the water on Earth was actually formed in space, in interstellar gas clouds. And it was delivered here when the Earth was formed, or shortly thereafter, in exactly the form it's in.

So all the water on Earth - the water in your Evian bottle, the water in your glass of water, the water you use to boil a pot of spaghetti - all that water is 4.3 or 4.4 billion years old. No water's being created on Earth. No water's being destroyed on Earth. And what that means is the whole debate about reusing wastewater is kind of silly, because all the water we've got right now has been used over and over again. Every drink of water you take, every pot of coffee you make is dinosaur pee, because it's all been through the kidneys of a Tyrannosaurus Rex or an Apatosaurus many, many times, because all the water we have is all the water we have ever had.

And to me, that's actually good news. Water is incredibly resilient. It's unlike fuel or other natural resources. It can be used over and over and over again, and it emerges - except for needing to be cleaned, ready to use again - exactly as water.

That's thinking of recycling well beyond the usual discussions of wash-basin to your lawn. He talks about that too and a lot more in a quite informative talk.

Did you know why the launch pad of the space shuttle is covered in a cascade of water during launch?

And you would naturally think that that has something to do with the heat and the flame. In fact, the water on the launch pad of a space shuttle launch is a sound-dampening mechanism for the space shuttle. The space shuttle is so loud that the sound would ricochet off the concrete and metal launch pad and tear the space shuttle apart, literally destroy it, before it cleared the pad without the water.

Listen / Transcript.

Pre Clovis Tools - American Archaeology and Earth Sciences

Science Friday had an entertaining talk with Michael Collins of Texas State University about the discovery of blades and spear points in Texas that pre date Clovis tools which are thought by many to represent the earliest people in the Americas.

From the transcript:

FLATOW: But why do you go deeper, where some other scientists might have stopped?

Dr. COLLINS: Well, we're working against an inertia, two inertias, really, that one has said for very many years that Clovis was the oldest culture in the Americas, at around 13,000 to 13,200 or 13,300 years ago. And some people haven't gotten over that, in spite of the fact for the last nearly 20 years we have had quite a few sites with strong indications of people being here before Clovis

.

And another thing - and that's improving. More and more people are accepting the concept or are at least willing to investigate it.

The other thing, the other inertia that we have, and it's also improving rapidly and greatly: American archaeology has - grew up in the social sciences. 

And not long ago, the vast majority of practicing archeologists in this country had very little background in the earth sciences and consequently didn't really think about the fact that okay, I have found cultural material here, I'm backing this excavation to Clovis, so that's the oldest culture, I'll just quit here, without thinking: You know, the dirt below that is just a little bit older. Why don't I look at that and see what's in it? There just wasn't that - that mindset was not particularly common. But happily, both of those things are changing for the better.

I find the stuff about the lack of earth sciences background hindering exploration a little hard to swallow. You don't need a background in earth sciences to motivate yourself to poke around in slightly older layers.

Just common sense..and perhaps overcoming the first inertia that a mainstream theory could be wrong.