Photo by Fred Spoor
Humans and all other apes alive today come from a common ape ancestor. While we already know quite a lot about our lineage dating back 10 million years, information is scarce beyond that. As a result, scientists still can't quite figure out the nature of the connection between apes and humans.
Over 40 species of apes arose during the Miocene epoch, which began 23 million years ago and ended five million years ago. The Miocene epoch, however, doesn't have the best fossil records.
Recently, the tiny fossilized skull of an infant ape was discovered in the Turkana Basin in northern Kenya. The infant belonged to a newly-named species, the Nyanzapithecus alesi. Not only was the skull the most complete one that belonged to an extinct ape, the infant had also lived during a critical time in African history. Thus, it can divulge quite a lot of information on a missing piece of our evolutionary history.
3D x-ray imaging of the skull
[Photo by Paul Tafforeau]
Researchers used a specially sensitive form of 3D x-ray imaging to be able to see into the inner parts of the skull. The 3D scans revealed the skull's brain cavity, the inner ears, and even the infant's unerupted teeth. It was through studying the teeth that researchers were able to determine that the infant had been around a year and four months old at death. Another thing that the teeth revealed is that the infant belonged to the Nyanzapithecus alesi.
The skull is tiny—about the size of a lemon. Initially, it was thought that the infant had belonged to an extinct species of gibbon, but it was eventually found that this was not true. The infant's appearance, though similar to that of gibbons, evolved in a number of different extinct apes and monkeys as well. The structure of the inner ears of the infant's skull also revealed that its species likely did not behave like gibbons. Gibbons move quickly, but the Nyanzapithecus alesi's inner ears revealed that members of the species moved more sedately.
The bony ear tubes in the infant's skull also reveal that evolution-wise, Nyanzapithecus alesi is a cousin to the ape ancestors of humans.
How small the skull is
[Photo by Christopher Kiarie]
There has long been a question—one of many—about the origins of humans and our ape cousins. Did our common ancestors evolve in Europe of Africa? Since the infant's skull fossil was found in Kenya, there's more evidence that the common ancestor of apes and humans had African origins.
The discovery of the tiny skull has answered a lot of questions. Scientists had long questioned whether or not Nyanzapithecus alesi were apes, along with a lot more missing information about the species. However, the analysis of the infant's skull has finally laid at least some of those questions to rest. For one thing, scientists are now sure that Nyanzapithecus alesi were apes. Though there are some who doubt that our common ape ancestors evolved in Africa, perhaps further study will lay these doubts to rest once and for all.
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