Wednesday, October 17, 2012

The Denisovans: A Look into Our Past

According to two recent articles in the LA Times, scientists have discovered and sequenced the genome of one of our close relatives: an extinct people known as the Denisovans, who lived in modern-day Siberia.

The genome itself was sequenced from a tiny DNA sampling extracted from shredded finger bone found in a Russian cave in 2008. A tooth was also found later
-Interesting to note that this sample of DNA gave as much detailed information about the individual as a DNA sample from blood or saliva extracted from a human today.
            -it suggests that the Denisovans had dark skin, brown hair and brown eyes

How the Denisovans fit into our evolution: Homo erectus (1-2 million years ago) à Denisovans, who left Africa as far back as 800,000 years ago à Homo sapiens left Africa perhaps 100,000 years ago

Analysis of this genome will offer insights into our own Homo Sapein history, as well as the unique changes that made us homo sapiens, and evolved us to stray away from the genetic make up of the Denisovans. Although discovering the thousands of tiny genetic differences between the two species, Svante Paabo and his coauthors have already highlighted several differences, including genes involved in writing the brain and ones that are known to be linked to autism.

This discovery leads us to question what other species are out there that can help us answer our complicated and much-debated history. Many say this discovery is just the beginning. However, the study found that about 3 to 5 percent of the DNA in people native to Papua New Guinea, Australia, the Philippines and other islands nearby came from Denisovans

Where we differ:
-About 100,000 places where single nucleotides, the individual building blocks of DNA, have changed so that one type of nucleotide has been swapped out for another
-About 10,000 places where a piece of DNA has been lost, or a new bit added.
-Found 260 changes that would alter a protein’s form by changing one of the amino acids it contains
-Found that we, homo sapiens, have 23 amino acid changes that the Denisovans and monkeys and apes DON’T have. 8 of these have to do with brain function and brain development, which strongly correlates with our ability to create larger, sustainable societies and have larger brains.
Yet at the end of the day, scientist Svante Paabo states, “Unfortunately, at the moment we know too little about the genome to really say what these things mean.”

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