Have scientists found The Missing Link?
For years, science has been in search of “The Missing Link” between early primates and early humans — a being that bridged the gap between the two very different species. On Tuesday, the announcement came that scientists have been waiting for.
Scientists are revealing a fossil this week that they say was found almost 30 years ago — and may help untangle the mystery of our connection with other mammals and our earliest human ancestors.
An international team of scientists announced in New York on Tuesday the discovery of a 47 million year old human ancestor. For the past two years, the team, led by world renowned Norwegian fossil scientist Dr Jørn Hurum of the University of Oslo Natural History Museum, have secretly run a series of detailed forensic tests of the extraordinary fossil. The team has been studying the data in an attempt to decode humanity’s ancient beginnings. As of the announcement on Tuesday, the research is 95% complete. The fossil, named Ida, and the information we’re learning from it is set to have a major impact on our understanding of human evolution.
Ida was originally discovered in Messel Pit, Germany — a crater near Frankfurt. The fossil is at least twenty times older than most other fossils involved in the chain of human evolution. Ida represents a member of a “transitional species”, which means Ida shows characteristics from the extremely primitive non human evolutionary line such as lemurs and other simians, but Ida is in fact more closely related to our human evolutionary line — animals such as monkeys, apes and humans. This transitional status places Ida at the very beginning of human evolution — a time when primates were first developing the traits that would evolve into our familiar human features. The international team’s findings have been published by PLoS ONE, the peer reviewed open access journal from the Public Library of Science.
Ida lived around 47 million years ago during a critical period in the history of the Earth. Ida’s lifetime fell within the Eocene Epoch, a time when scientists believe the “blueprints” for modern mammals were being established. After the mass extinction of dinosaurs, early horses, whales, and many other and and sea based creatures (including the first primates) were able to thrive on Earth’s subtropical climate. The Earth was then just beginning to take the shape that we are familiar with today — modern animals and plant life were evolving, and famous geological features like the Himalayas were being formed. Land mammals, including primates, lived in enormous jungle landscapes. This is where Ida most likely lived — a massive jungle like region buzzing with plant and animal life.
So how do we know Ida wasn’t just another lemur? The researchers have found that Ida lacks two of the key anatomical features normally found in lemurs: a grooming claw found on the second digit of the foot, and a feature known as a “toothcomb”, which is a row of fused teeth in the middle of her lower jaw. Also, rather than having claws (which are typical of primates on the level of lemurs) Ida has nails, and her teeth are almos identical to teeth found in monkeys. Most enchanting of all, her eyes are very similar to human eyes. They face forward, allowing her two fields of vision to overlap. This is important, as overlapping vision allows 3D processing and a heightened ability to judge distances.
Ida’s hands show opposable thumbs — found in humans, but not lower primates. Like all primates, Ida has five fingers on each hand. The presence of an opposable thumb would have provided an advantage in terms of a strong grip. In the case of our relative Ida, this grip is useful for climbing and gathering fruit, while for humans, the opposable thumb grip allows functions such as making tools, communicating, and writing. According to the researchers of the fossil, Ida also had incredibly flexible arms, which would allow her to use both hands at once. Many tasks can’t be accomplished with just one hand (imagine trying to grab a piece of fruit off a tree with just one hand) so the ability to use both hands no doubt propelled Ida and her kind to the top of the food chain. Like humans, Ida has quite short arms and legs when compared with other lower order primates.
There are a few famous primate fossils who have been given names — “Lucy”, a primate fossil found in the Cradle of Mankind in Africa, was so named because the song “Lucy in the Sky with Diamonds” was playing during the party after her discovery. But unlike Lucy and the other famous primate fossils found in Africa, Ida is a European fossil who was preserved in Germany’s Messel Pit. The Messel Pit is a mile-wide crater, a significant site for fossils from the Eocene Epoch. The scientist’s fossil analysis has revealed that the prehistoric primate was a young female. Her opposable big toes and the presence of nails in place of claws helped confirm that the fossil “Ida” is a primate, while a foot bone found in Ida’s fossil (called the “talus bone”) provides a direft link from Ida to modern humans.
X-rays reveal that a broken wrist may have been involved in Ida’s death — scientists are not sure why or how, but there is evidence that her left wrist was in the process of healing from a particularly nasty fracture. One possible explanation that the research scientists have come up with — perhaps Ida was overcome by carbon dioxide gas while stopping for a drink from Messel lake. We know that the lake’s waters were often covered by a low lying fog of CO2, due to volcanic forces that formed the lake and were still active at the time of Ida’s life. Though this is pure speculation, it provides a nice window into life 47 million years ago. Overcome by the CO2 gas, Ida fell and broke her wrist, was unable to find food or simply slipped into unconsciousness, at which point she was washed into the lake where particularly unique preservation conditions allowed her fossil to stay well intact for almost 50 million years, until she was discovered in 1983.
The fossil of Ida also features a complete ‘soft body outline”, showing what her original body may have looked like. We also know a ton about Ida’s diet, as her “gut contents” were well preserved: Ida was a vegetarian, eating lots of fruit, seeds and leaves. X-rays of the fossil show that Ida still had a few “baby teeth” as well as a few adult teeth, placing her age somewhere in young adolescence. The X-rays also confirmed the lack of a ‘toothcomb’ or a ‘toilet claw’ , the two attributes of lemurs discussed above. Scientists estimate Ida’s age when she died to be approximately nine months, and she measured approximately three feet in length.
Further evidence linking Ida to us lies in that all important talus bone. The bone in Ida has the exact same shape as it does in humans today. The one difference is size — obviously, the human talus bone is larger, as Ida is only three feet in length. Using X-rays, CT scanning, and other computer based tests, scientists were able to pick apart the well preserved fossil without destroying it. More information about Ida will continue to surface as tests of her fossil continue. For now — we have a new ancestor. Let’s all welcome Ida to the pack.