Its Hard To Classify That Archaeopteryx

How birdlike was Archaeopteryx?

Beak - Yes
Feathers - Yes
Wishbone - Yes

Growth pattern of blood vessels - Not quite there yet

By comparing the structure of the bone of Archaeopteryx with modern birds and fossil dinosaurs, researchers found out the growth pattern of blood vessels in Archaeopteryx was more like dinosaurs than modern birds. Archaeopteryx individuals seem to have taken a longer time to mature than modern birds do.

Archaeopteryx lived about 150 million years ago and is the earliest bird-like creature to have been found yet.  A younger bird-like fossil -Ichthyornis dispar - dated about 94 million years ago shows several characteristics of quick growth, giving us an idea of the timing of the various changes in morphology and physiology that were taking place within the Maniraptor dinosaurian clade as they evolved  characteristics that are recognized as bird-like.

By the way this is not some earth shattering find. The basic relationship that  small carnivorous dinosaurs evolved into birds still holds. But the study highlights how difficult categorizing a creature which is a composite of ancestral and derived traits can be.

It doesn't matter in the larger view if Archaeopteryx is classified as a dinosaur or a bird. The value is in demonstrating that evolution of a complex suite of characters takes place in fits and starts, some features evolve earlier than others preserving the historical trajectories that major transitions in evolution have taken.

Go here for the lighter version.

Physicist Extraordinaire- Science Friday On A New Book On Paul Dirac

Science Friday has a really interesting talk with Graham Farmelo on his new book on Paul Dirac - The Strangest Man: The Hidden Life of Paul Dirac, Mystic of the Atom.

What's my connection to this great man? Later in his career Paul Dirac joined Florida State University, Tallahassee which was my Alma mater too. I walked often past his statue on the way to the Dirac Science Library. 

Farmelo gives a good account of Dirac in that talk as a reticent personality, who avoided people...but not unaware of the importance of knowing the right people....he did make sure he was standing right behind Einstein in a group photo at a conference.

Meanwhile from my book shelf in one of the best science autobiographies I have read- Sir Fred Hoyle's vibrant and entertaining Home Is Where The Wind Blows- I found the following nuggets about Hoyle's interaction with Dirac:

Shortly after inveigling me into the secretaryship of the Delta-Squared V Club, Maurice Pryce left Cambridge to take up a lectureship at Liverpool University. If I was to retain my student status with the Inland Revenue, another research supervisor was therefore needed. Pryce suggested Dirac, so I went to Dirac and explained the situation. Although normally he didn't accept  students, Dirac broke his rule on this occasion because he simply couldn't resist the circular counterlogic of a supervisor who didn't want a research student who didn't want a supervisor.

and...

More than any other person I have known, Dirac raised the meaning of words and syntax to a level of precision that was mathematical in its accuracy. He had nothing at all of the irritating habit of attempting to read hidden significance  into your remarks. He paid everybody the compliment of supposing they knew exactly what they were saying, a compliment he sometimes took to extreme lengths.

how great was Dirac..?.......like truly great minds he is posthumously productive...  says Farmelo.

Indian Groundwater Extraction May Be Contributing To Sea Level Rise

I don't know what to make of this calculation which I picked up in a New Scientist story. A few weeks ago there was a study using NASA's Grace satellite measurements that showed an increase in groundwater extraction from North Indian aquifers.

A second study on these satellite measurements asserts that the groundwater loss amounts to about 54 cubic km per year over a time period of 2002 and 2008. A lot of this extracted groundwater ends up in the sea and could be contributing to raising sea-levels by 0.16 millimeters every year, about 5% of the total sea level rise. That is about the same as contributed by runoff from melting Alaskan glaciers the authors conclude.

I don't have access to the full paper so I don't know the details of the calculation but here is what the scientists have to take into account:

Part of the groundwater extracted will be taken up by plants and remain there over the life of the plant and make its way into the food chain.
Part of it will be lost through the plants through evapo-transpiration.
Part of the water will remain in soil adhering to clay and sand particles.
Part of it will make its way back to the aquifer.
Part of it will make its way through the soil to local streams and eventually to the sea.
Part of it will be lost by direct evaporation. That evaporated water (and the water lost by evapo-transpiration) will fall as rain and part of it will infiltrate as groundwater and part of it will be surficial runoff into streams and eventually into the sea.

Just giving you  something to think about what happens to extracted groundwater.

Not Left Out! My Interview At The Reef Tank Is Online

There is a geology bonanza going on over at The Reef Tank which is a blog and forum dedicated to marine science topics including climate change, marine energy, ocean acidification and marine conservation. There have started a marine geology section in their community blog. Brian@ Clastic Detritus was the first to be interviewed. Dr. Erik W. Klemetti of Eruptions was second. The Lost Geologist was interviewed a few days ago.

Now its my turn. My interview is online (thanks to Brian who recommended my name) on their community blog page. I thought the questions were quite challenging and interesting dealing with how carbonate sedimentology relates to marine sciences and ecosystems and what my background in carbonates tells me about the current crises marine ecosystems may be facing due to global warming. There were a couple of questions on my posts on groundwater.

My favorite question though and I thank Ava the blog moderator for asking that-

You also blog on evolution. How important was/is marine life and marine ecosystems to the theory of evolution and why? 

I got a chance to write about how carbonate sediments help us understand evolution and also the question gave me a chance to highlight the work of two of my advisers who inspired me into studying carbonates and evolution.

Go over to The Reef Tank and take a look.

Genetic Ancestry of Indians. A New Paper Is Creating a Ruckus

A new paper about the genetic history of Indian populations in Nature is making waves in press releases. A reader asked me if I could explain the finding in plain english. Since I am not an expert in population genetics I will instead point to two posts that have dissected the paper. John Hawks writes about the topic here. Gene Expression details it here.

The salient points as I understand:

1) This is not some pioneering work as some of the Indian press reports suggest it is. The broad finding of this study have antecedents and are not that surprising or shocking.This study though does expand on earlier work by using a larger number of genetic data points and so is significant in its scope.

2) Modern Indian populations are derived from two ancient populations referred to as the Ancestral North Indians (ANI) and the Ancestral South Indians (ASI). Ancestral North Indians were Caucasoids, genetically closer to Eurasians, Europeans and central Asians while the Ancestral South Indians  were distinct from Caucasoids and Mongoloids. The Onge of the Andamans are a good model for the original Ancestral South Indians. The modern Indians are admixtures of these two populations (the Onge are not ancestral but an early branch of the ASI)

3) The findings indicate that there is a larger amount of genetic variation between Indian groups than there is between say European groups. This the authors suggest is a result of a small number of individuals founding different ethnic groups that then remained endogamous and therefore genetically divergent. This has important medical value as recessive diseases may correlate with ethnic groups.

4) Despite these inter group differences on average Indians from various groups and across castes are more closely related to each other than they are to outgroups like Europeans or East Asians. This points to the deep residence time of people in the subcontinent and continued gene flow across groups. This has led to reporting in the press that there is no north south divide and the Aryan-Dravidian divide is a myth. Again this finding is not new. There is earlier work that suggest similar genetic relationships among Indians.

5) The study also clearly shows that for some genetic lineages there is a gradient in relationship to ANI (west Eurasian) that is a function of geography and caste. For some genes north Indians (Indo European speakers) and upper castes are more closely related to ANI than are south Indians and lower castes. Here is a table that summarizes this result. The first few samples in the table are from south India (Dravidian and Tribal) and the lower portion of the table represents north Indians (Indo-European speaking people).

6) The paper says little about when this admixture with west Eurasian genes occurred but hints it may coincide with the arrival of Indo-European speakers which has generally been timed post collapse of the Harrappan city states around 1800 - 1600 B.C. This is off course is a controversial topic. The amounts of admixture with ANI is high in some samples. This may be taken by some as a validation of the Aryan Invasion scenario in which there was a massive migration and population replacement of indigenous people in northern India by Indo-European tribes. I don't see it that way. The northwestern region has always been a conduit into India. There would have been people movements from the Central and West Asia into this region related to the spread of agriculture (6000 - 8000 B.C ?). City states like the Harrapan complex had extensive trading ties (2600 - 2000 B.C) with the Bactria Margiana Complex in the Turkmenistan - northern Afghanistan - Tajikistan - Uzbekistan area and with the Elamite civilizations in western Iran. The people involved in trading  with these city states included those from the Pontic -Caspian Eurasian steppes.

So it is unlikely that any one historical event shaped these genetic relationships. Migration and population movements of Caucasoid people into India have been taking place longer than the advent of the Aryans although it does seem that the arrival of Indo-European speakers did leave a recognizable genetic imprint on older Indian populations. 

7) The Indian Press has made a hash of the finding. For example they have only reported those parts of the study that deal with the kinship among Indians and have stressed that castes and tribes cannot be differentiated or that there is no divide between the Aryans (roughly north Indians) and Dravidians (south Indians). That is all true for average relatedness. But the study also clearly points out that there are genetic differences between north and south Indians and between upper and lower caste in terms of the degree of relatedness to Eurasians. North Indians and upper castes are more closely related to  Eurasians. North Indian upper castes have even more Eurasian ancestry. This part was ignored by the press.

But I can't blame the press entirely. The scientists who gave interviews to the press didn't mention this. They wimped out on reporting this potential inflammatory and politically incorrect finding. This is just poor and irresponsible science outreach on part of the scientists. How can you ignore a finding that is staring out at you from the very paper you are talking about? The press may be guilty of not digging in but it was just reporting what the scientists told them.