Our closest relatives -- gorillas, orangutans, chimpanzees, gibbon apes and baboons -- have now been joined by an animal whose appearance hardly resembles that of humans: the flying lemur.
Flying lemurs (Dermoptera) live in Southeast Asia. The largest species can be 75 cm tall. This animal can glide between trees, thanks to skin stretched between the front and back legs.
The discovery of our new relative was made by a research team headed by Professor Ulfur Arnason of the department of Evolutionary Molecular Systematics at Lund University in Sweden. It is reported in the current issue of the Proceedings of the National Academy of Sciences (PNAS).
“Flying lemurs have the same ancestors as the Anthropoidea, that is, apes from the New and Old Worlds, including human beings. We are more closely related to flying lemurs than we are to half-apes,” says Professor Arnason.
In the classical division of the higher mammals (Eutheria), there are 18 orders in this class. This is based on observations of the structure of the organisms.
But today, scientists also examine how various species are related to each other biochemically, by analyzing and comparing their genes. Researchers are working with molecules of mitochondrial DNA, which has been sequenced in its entirety.
Arnason and his associates have now added 11 new complete mitochondrial DNA molecules to the mammalian evolutionary tree. In total, the analysis is based on comparisons of 60 species of mammals.
“What this and earlier studies have shown,” continues Professor Arnason, “is that the classic orders are not as self-evident as we previously thought.
"In 1994, David Irwin and I discovered that whales and even-toed hoofed animals were not separate species; instead whales evolved from a special branch of even-toed hoofed animals. This branch is represented by the hippopotamus. Thus there is a closer relation between whales and hippopotamuses than between whales and any other now extant even-toed hoofed animals.
“In the present paper, we also show that the classical order of insect-eaters (Lipotyphla or Insectivora) consists of not one but three orders: hedgehogs, tanrecs, and shrews/moles. Suddenly there are 20 orders instead of 18. But we have also shown that one of these orders, namely Dermoptera, or flying lemurs, belongs in the order of primates as the closest relative of Anthropoideas. This means that those 20 orders have now been reduced to 19."
The PNAS paper is titled “Mammalian mitogenomic relationships and the root of the eutherian tree.”
(Editor's Note: Meerkat's Mammals has this page on flying lemurs. It was posted prior to Professor Arnason's PNAS paper.)
[Contact: Professor Ulfur Arnason, Göran Frankel]