Wednesday, September 17, 2008

Some Good Evolution Talks On NPR

I listen to Science Friday on Sunday. It's an old habit. I usually keep aside an hour or so, select what I want to listen to and then make some hot chai in preparation. Not the insipid hot water you get at overpriced coffee shops but real chai with milk, sugar and ginger. Then its podcast time. This week three good talks on evolution.

The first one was a short summary of a pretty important discovery. A gene sequence named HACNS1 that regulates gene activity most notably in the thumb, wrist and ankle. James Noonan one of the researchers explained that a comparison of this sequence with other species showed evidence of considerable evolution in the human version. They got the human version to express itself in genetically engineered mice and it triggered gene activity in the thumb and wrist area. The image below shows expression in the thumb of transgenic mice. The blue color is due to a reporter gene inserted along with HACNS1 to make it easier to identify areas where HACNS1 was being expressed.

Source: Yale Univ.

This may be one of the genes that gives dexterity to our forelimbs and digits. A natural question that came to me was when in our history did HACNS1 diverge from the ancestral version shared with early chimpanzees. I wish they had invited an anthropologist to give a fossil perspective. I dug around some literature and found out that early Australopethicines around 3.5 million years ago already had opposable thumbs different than chimpanzees and gorillas do. So looks like HACNS1 had diverged from the version inherited from the common ancestor with chimps by at least 3.5 to 4 million years ago. Maybe even much earlier if HACNS1 influences ankle development as well. Does it play a role in bipedality? The earliest bipedal hominids go back almost 6 million years.

The second talk was about the release of the new evolution game Spore. The game creator Will Wright along with beta tester evolutionary biologist Richard Prum discussed the game and what we can learn about evolution. Here's how a NYTimes report describes it:

The game begins with a meteorite crashing into a planet, sowing its oceans with life and organic matter. Players control a simple creature that gobbles up bits of debris. They can choose to eat other creatures or eat vegetation or both. As the creature eats and grows, it gains DNA points, which the player can use to add parts like tails for swimming or spikes for defense. Once the creature has gotten big and complex enough, it is ready for the transition to land.

And so on... The games focuses on adaptation and natural selection and so has been criticized for leaving out many other important mechanisms of evolution. No random genetic drift, no migrations and demographic shifts for example. Will Wright defended his approach, in effect saying that the intent was to get people interested in evolution. There are then many other formal avenues for detailed study . I agree with him. It's a game. Have fun. The problem is not that this one game doesn't represent evolution accurately, but that evolution is not covered adequately in school and even college level around the world. Fix that first.

And finally for those who like to unwind with a tall cool one. A talk on the biology and evolution of yeast that are used to ferment ales and lagers. Gavin Sherlock a geneticist from Stanford University discusses these life saving yeasts. Ale was around earlier. Then at some point, two ale yeast strains hybridized to form a new lager yeast. Hurray for the monk who supervised this momentous transition (did anyone else make beer in those days? :)) Lots more in this talk about beer and yeast.

Unfortunately I had had too much chai to switch to a frosty!

1 comment:

  1. yeah this is infact a very nice article deciphering and highly conserved enhancer.......;which is rapidly evolving in humans and might be regulating a gene ,which might play a role in hand development.....As this experiment is done in mouse ..;;so one cannot be sure if this enhancer regulates a hand specific gene in humans there will be different trans acting factors in mouse.chimps and humans....unfortunately this was the best they could do.......Thanks suvrat for the the information about science friday site........its really informative.......