neurosciencestuff:

New genetic data shows humans and great apes diverged earlier than thought

To calculate when a species diverged, researchers look at the average age of members of the species when they give birth and mutation rates. The older the average age, the more time it takes for mutations to cause changes. Insects that produce offspring in a matter of months, for example, can adapt much more quickly to environmental changes than large animals that produce offspring many years after they themselves are born. To find such data for both chimps and gorillas, the research team worked with many groups in Africa that included studies of the animals that totaled 105 gorillas and 226 chimps. They also looked at fossilized excrement that contained DNA data. In so doing they found that the average age of giving birth for female chimps was 25 years old. They then divided the number of mutations found by the average age of birth to get the mutation rate. In so doing, they found it to be slower than humans, which meant that estimates based on it to calculate divergence times were likely off by as much as a million years.

The end result of the team’s research indicates that humans and chimps likely diverged some seven to eight million years ago, while the divergence of gorillas (which led to both humans and chimps) came approximately eight to nineteen million years ago. To put the numbers in perspective, humans and Neanderthals split just a half to three quarters of a million years ago.

uprightbipedalist:

Last but not least of the great apes!

oldowan:

Orangutans Harbor Ancient Primate Alu

 Alu elements infiltrated the ancestral primate genome about 65 million years ago. Once gained an Alu element is rarely lost so comparison of Alu between species can be used to map primate evolution and diversity. New research published in BioMed Central’s open access journal Mobile DNA has found a single Alu, which appears to be an ancestral great ape Alu, that has uniquely multiplied within the orangutan genome.

Analysis of DNA sequences has found over a million Alu elements within each primate genome, many of which are species specific: 5,000 are unique to humans, while 2,300 others are exclusive to chimpanzees. In contrast the orangutan lineage (Sumatran and Bornean orangutans) only has 250 specific Alu.

These tiny pieces of mobile DNA are able to copy themselves using a method similar to retroviruses. But, because this is an inexact process, a segment of ‘host’ DNA is duplicated at the Alu insertion sites and these footprints, known as ‘target site duplications’, can be used to ‘identify’ Alu insertions. Alu elements can be thought of as molecular fossils, and a shared Alu element sequence and location within the genome indicates a common ancestor.

oldowan:

THANKS to Kamilah the gorilla, the last of the great apes has had its genome fully sequenced. The results highlight key similarities between us and gorillas - our second closest relatives after chimps.

Richard Durbin of the Sanger Institute in Cambridge, UK, led the international team that pieced together the western lowland gorilla (Gorilla gorilla gorilla) genome using several different sequencing techniques. The genome contains more than 3 billion pairs of DNA letters - roughly the same as humans - and includes about 21,000 genes.

oldowan:

Chimpanzee populations living in close proximity are substantially more different genetically than humans living on different continents, according to a study published in PLoS Genetics. Research conducted by scientists from the universities of Oxford and Cambridge, the Centre Pasteur du Cameroun, and the Biomedical Primate Research Centre suggests that genomics can provide a valuable tool for chimpanzee conservation, with the potential to identify the population of origin of an individual chimpanzee or the provenance of a sample of bush meat.

nonhumanprimates:

“Due to billions of years of evolution, humans share genes with all living organisms. The percentage of genes or DNA that organisms share records their similarities. We share more genes with organisms that are more closely related to us. 

Humans belong to the biological group known as Primates, and are classified with the great apes, one of the major groups of the primate evolutionary tree. Besides similarities in anatomy and behavior, our close biological kinship with other primate species is indicated by DNA evidence. It confirms that our closest living biological relatives are chimpanzees and bonobos, with whom we share many traits. But we did not evolve directly from any primates living today.

DNA also shows that our species and chimpanzees diverged from a common ancestor species that lived between 8 and 6 million years ago. The last common ancestor of monkeys and apes lived about 25 million years ago.”

claudiaselene:

Did you know, that the difference between a human being and a primate’s DNA is only 2%?

Depends upon the primate. But let’s focus on great apes for right now.

Some research, which is the more often cited number, suggests the closeness in the variation in genetic code between humans and great apes:

Results published by Sibley and Ahlquist reveal that humans and chimpanzees have the most similar DNA (Sibley, 1984). They converted the melting temperatures of the DNA hybrids into phylogenetic distances (change in T5OH values) and found that the distance between humans and chimpanzees is 1.64; the distance between humans and gorillas is 2.27; the distance between humans and orangutans is 3.6; the distance between humans and gibbons is 4.76; and that the distance between chimpanzees and gorillas is 2.28. In other words, humans share 98.4 percent of their DNA with chimpanzees and differ by only 1.6 percent.

This research tends to look at equivalent genes between apes that differ solely in whether they are active (“turned on”) or not. 

More recent research, which takes into account differences between genes and duplications of these, suggests a much greater variation between humans and chimpanzees, placing it closer to 6 percent.

Another key thing to remember: Humans have 46 chromosomes, or 23 pairs; all other great apes have 48 chromosomes, or 24 pairs. From PBS:

Scientists offered two possible explanations for the discrepancy: Either the common ancestor had 24 pairs, and humans carry a fused chromosome; or the ancestor had 23 pairs, and apes carry a split chromosome. Their focused research led them to find a mutation on one human chromosome that explained what had happened.

In 2005, a peer-reviewed scientific journal published results of the tests. It turns out that chromosome 2, which is unique to the human lineage of evolution, emerged as a result of the head-to-head fusion of two ancestral chromosomes that remain separate in other primates. Three genetic indicators provide strong, if not conclusive, evidence of fusion. First, the banding (or dye pattern) of human chromosome 2 closely matches that of two separate chromosomes found in apes (chimp chromosome 2 and an extra chromosome that does not match any other human chromosome). Second, a chromosome normally has one centromere, or central point at which a chromosome’s two identical strands are joined. Yet remnants of a second, presumably inactive centromere can be found on human chromosome 2. And third, whereas a normal chromosome has readily identifiable, repeating DNA sequences called telomeres at both ends, chromosome 2 also has telomere sequences not only at both ends but also in the middle. 

The Smithsonian Institution’s Human Origins exhibit and website provides a great resource as well, if you’re interested in human evolution and differentiation from great apes and other primates.

And there’s your human-great apes genetics lesson of the day.

ericmjohnson:

A new international study of primate evolution has just been published in PLoS Genetics offering the most comprehensive phylogeny to date. But there is one detail in the study that I’m surprised hasn’t been picked up on in any of the news reports I’ve seen about this study:

Based on 54 gene regions, Homo-Pan genetic distance range from 6.92 to 7.90×10⁻³ substitutions/site (P. paniscus and P. troglodytes, respectively), which is less than previous estimates based on large scale sequencing of specific regions such as chromosome 7.

In other words, bonobos appear to share 12.4% more DNA in common with humans than chimpanzees do. This is more than twice the genetic divergence in squirrel monkeys (genus Saimiri) and adds further evidence suggesting that bonobos are a better model for understanding our common ancestor than chimpanzees are.