Hand and foot remains found in Kenya suggest ancient human relatives

Researchers in northern Kenya have discovered fossils of the hand and foot bones of an extinct human relative that dates back to 1.52million years ago. This species was able to manipulate stone tools, and would have been fully bipedal.

The fossils were the first to be unambiguously associated with the species Paranthropus boisei. Researchers found a partial skull that contained a large portion of the hand and three foot bones. They also discovered most of teeth, a forearm fragment, a partial tooth, and a fragment of a skull.

The new discovery is a revelation, especially when you consider the fragmentary nature previous fossils.

This species is a descendant of Homo Sapiens, who evolved much later.

Paranthropus bossei had a robust build with massive teeth and strong jaws. The skull of Paranthropus boisei was designed for chewing tough plant food. It had a crest on top to anchor the large jaw muscles. Flaring cheekbones gave it a dish shape. It was difficult to know the species without hand and foot fossils. This included whether it could have made and used simple tools.

The study, published in Nature this week, was led by paleoanthropologist Carrie Mongle, a researcher at Stony Brook University, New York.

The fossils have been discovered on the eastern shore of Lake Turkana in a place called Koobi Fora.

Before this discovery, researchers were only able to study the dental and cranial remains, but very little else was known about this species' skeleton, said Louise Leakey of the Koobi Fora Research Project, a paleoanthropologist who co-authored the study.

Mongle stated that the hand bones showed it was able to form precision grips like modern humans. This suggests this species could have made and used stone tools.

Leakey stated that the handshake would have been very firm. We can tell that this species' hand was built to be able to hold firmly and for a long time. It would have been similar to gorillas as it would have used the hands to break down tough plant food, such as tearing, crushing or stripping vegetation. This is consistent with their hard and fibrous dietary habits, seen in its robust dentition.

Fossils also revealed the species' locomotion. It was well adapted to walk upright on two feet.

Leakey explained that "we can tell from its few foot bones that it is fully bipedal and not flat-footed, like a monkey, and that it would have had a similar lateral arch to ours which would have propelled the animal forward as it walked."

Hominins are species that have evolved from humans. Paranthropus boisei is one of the four hominins that shared East Africa's landscape between one and two millions years ago. There have been discoveries of stone and bone tools dating from this period, but it is unclear if Paranthropus could have made and used them.

Genus is a term used to describe a grouping of closely related species. Our species belongs to Homo. Homo, Homo Rudolfensis, and Homo Erectus are extinct species that lived in East Africa at the same time as Paranthropus.

Some of these species literally crossed paths. In a study published in 2013, Paranthropus erectus and Homo boisei left footprints that crossed each other at Koobi Fora, a once muddy lakeshore. This discovery raised interesting questions about the relationship and competition between the two species for resources.

Mongle explained that "Conventional Wisdom" has it that, while Homo was specialized in bigger brains and stone tools that allowed them to adapt well to changing climates, Paranthropus became a grass-focused dietary specialist.

Leakey stated that the Paranthropus eventually went extinct.

(source: Reuters)