rfmcdonald | [LINK] Two primate links (Reply)

Both of these are from the ever-interesting io9. Thanks for pointing me to it, Glenn!

First comes the news that chimpanzees have the ability to generate and transmit cultural elements, to wit, the ability to undo snare traps.

The snare traps are used in the Bossou region of Guinea primarily to capture cane rats. The locals don't eat chimpanzees because the chimpanzees are thought to be the reincarnation of their ancestors, but the snares will trap and kill anything that wanders inside. Still, the Bossou chimpanzees suffer far fewer snare deaths than their counterparts elsewhere, and it's all because they've learned how to avoid this deadly fate.

Researchers from the Japan Monkey Center observed five different male chimpanzees deactivate snares on six separate occasions. Once, they saw a chimp shake a snare until it broke. Another time, a group of adult chimps and a juvenile male came across a trap. The youngest chimp then managed to make the ropes holding the snare together become untied, rendering the trap harmless. All these chimps seemed quite expert and none met with any injuries - indeed, any mistake made would have almost certainly killed or maimed the chimp.

The researchers believe these behaviors have actually been passed down from generation to generation, which is supported by the fact that the juvenile chimp handled the deactivation when it's highly unlikely he was the most experienced of the party. Only the chimps in the Bossou region have displayed this ability. It's possible that this all comes from an individual chimp a few generations back who escaped a snare and passed down these behaviors to all that followed.

What's really amazing is that it isn't one specific action the chimps use to destroy the snares - multiple methods are used, suggesting the chimps really do perceive the snare as a general threat that can be dealt with using different strategies, and not just a stimulus that provokes a particular unthinking response.

Second, we learn that orangutans are genetically quite diverse despite having evolved little.

The family Hominidae, commonly known as the Great Apes, has four main members: humans, chimpanzees, gorillas, and orangutans. Humans and chimpanzees are the most closely related species, and then both are more related to gorillas than orangutans, who are all alone on their corner of the family tree. Orangutans are now the latest members of the great ape family to have their genomes sequenced, and they've revealed some surprising details about our evolutionary story.

The most shocking has to be that the orangutan genome hasn't changed in 15 million years. To put that in some perspective, our species didn't even really exist until 200,000 years ago, and even the Homo genus doesn't stretch much further back than 2.4 million years. Chimpanzees don't become distinct from our evolutionary ancestors until about six million years ago, and gorillas don't emerge until about 7 million years ago. Orangutans are, by the standards of the rest of their family, an incredibly ancient species.

The key difference is that the orangutan genome evolved very slowly, without any of the rapid-fire bursts of acceleration that we can find preserved in the genomes of humans or chimps.

[. . .]

Part of the puzzle seems to be a kind of DNA element known as "Alu". Alus are repetitive stretches of DNA that comprise about 10% of our genome and can account for unexpected mutations that help drive evolution. Humans have about 5,000 of these Alus, chimps have 2,000, but orangutans [have 250].

Still, after 15 million years of genomic slumber, orangutans woke up about 400,000 years ago, diverging into the Sumatra and Borneo species. Intriguingly, modern orangutans - particularly the Sumatran orangutans - have incredibly diverse DNA, which seems counter-intuitive considering their evolutionary history. Locke explains:

Go, read.