Tarsiers and Humans are Distant Cousins, Study Suggests

It has been long debated where the tarsiers belong into the evolutionary primate tree. Now, a new genome study can finally answer the question and end the controversy once and for all. The study, published in the journal Nature Communications, revealed that tarsiers belong to the same branch in the evolutionary tree that lead to monkeys, great apes and humans.

Scientists have been baffled by the unique characteristics of tarsiers. Despite its small size, tarsiers are formidable nocturnal hunters. As the only exclusively carnivorous primate, tarsiers have developed a full suite of weaponry to help it hunt insects, small birds, rodents and lizards. These weapons include large eyes twice as big as their brain, a head that can rotate 180 degrees in each side, ability to track prey using ultrasound, legs and feet adapted for powerful leaps and an elongated ankle bone.

"We sequenced the tarsier not only to determine where they fit in primate evolution, but because their physiology, anatomy and feeding behavior are very unique," said Wesley Warren, PhD, an associate professor of genetics and senior author of the study, in a press release.

For the study, the researchers analyzed DNA sequences known as transposons, or "jumping genes." These jumping genes can jump from one part of the genome to another. During this process, jumping genes often duplicate themselves. However, transposons may lose their ability to jump overtime.

Newer transposons can jump into older transposons, but not vice versa. Due to this, the researchers could determine when particular families of transposons lost the ability to jump by analyzing which transposons were embedded inside others.

The researchers then compared transposon families of tarsiers, humans, bushbabies (a wet-nosed primate) and squirrel monkeys (a dry-nosed primate). The researchers noted that tarsiers share their more recent transposon families with the squirrel monkey and human, while their oldest transposon families share similarities with the bushbabies. This suggests that tarsiers are more closely related to dry-nose primates than wet-nose primates despite sharing some features with the two categories.