Evolutionary history of a species—skull fossil could change the human genus

A a coelacanth, Latimeria chalumnae Smitha, or living fossil fish on display in the Untied States National Museum. (Courtesy of Smithsonian Institution Archives)

A a coelacanth, Latimeria chalumnae Smitha, or living fossil fish on display in the Untied States National Museum. (Courtesy of Smithsonian Institution Archives)

The evolution of humans is a branch of science that continues to, well, evolve, particularly when it comes to the evolutionary history of a species such as the human genus, Homo. Mankind may undergo yet another update thanks to the discovery of Skull 5, a 1.8-million-year-old skull fossil uncovered in the republic of Georgia eight years ago. But it isn’t just humans that are learning new things every day about how mankind came to be—scientists are also uncovering new insights into the evolution of a host of creatures, from mammals to fish.

Ever-evolving understanding

After eight years of study, an international team of scientists led by David Lordkipanidze, a paleoanthropologist at the Georgian National Museum in Tbilisi, believe they may have new insight into the evolutionary history of the human genus. John Noble Wilford reported on October 17, 2013, in “Skull Fossil Suggests Simpler Human Lineage” for The New York Times, that the findings may mean “a simpler story with fewer ancestral species. Early, diverse fossils — those currently recognized as coming from distinct species like Homo habilis, Homo erectus and others — may actually represent variation among members of a single, evolving lineage.”

Described as “‘the world’s first completely preserved adult hominid skull’ of such antiquity,” the fossil possessed a number of primitive features, making it unlike other Homo fossils. These features included a long, apelike face, large teeth and a tiny braincase. According to Wilford’s article, the braincase was “about one-third the size of that of a modern human being.” To scientists, this means that a big brain was not required by early hominids to leave Africa.

From human genus to mammals

But it isn’t just our human ancestors that are undergoing a shift in evolutionary history. A fossil discovered in Inner Mongolia, China, reveals the evolutionary adaptations of a 165-million-year-old proto-mammal. Scientists say the recently discovered fossil gives evidence “that traits such as hair and fur originated well before the rise of the first true mammals,” according to a post on phys.org, from August 7, 2013, “New proto-mammal fossil sheds light on evolution of earliest mammals.”

The fossil, Megaconus, is from the Jurassic era, nearly 100 million years before Tyrannosaurus Rex roamed Earth. It lived alongside feathered dinosaurs and was found with a “clear halo of guard hairs and underfur residue, making Megaconus only the second known pre-mammalian fossil with fur” according to the post. The exciting takeaway for the scientists is that the fossil shows “many modern mammalian biological functions related to skin and integument had already evolved before the rise of modern mammals.”

A living fossil

The Independent relates another take on the evolutionary history of a species, or perhaps not, in “The ‘Living Fossil’ Fish Left Behind by Evolution” by Steve Connor, published on April 18, 2013.

The coelacanth is a deep-sea fish which has become known as a “living fossil.” This designation comes as a result of the fact that the fish has not changed in appearance since before the time of the dinosaurs. The reason for this lack of evolution Connor relates comes courtesy “of an extraordinary genome that is barely evolving.”

A study found that the fish, which lives in deep-sea caves off the coast of Africa, was thought to have gone extinct at least 70 million years ago. But in 1938, a dead specimen was discovered by South African fishermen. During those intervening years, the coelacanth was one of the few species that hardly changed in tens of millions of years. Connor writes that “now scientists believe this stability is mirrored in the coelacanth’s genome – the 3 billion ‘letters’ of its DNA code.”

Coelacanths don’t need to evolve quickly, according to the study published in the journal Nature that Connor reports on “because they live in the relatively unchanging environment of deep-sea caves where there are few predators.”

The evolutionary history of a species, whether man or fish, is a fascinating and constantly changing area of science. Want to learn more about life sciences, particularly the topic of evolution? Check out Questia

What do you think about what the discovery of Skull 5 means for the evolution of human? Let us know your thoughts in the comments.

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