[Prehistory 101 {Human origins}.]

The story of humanity's evolution began about seven million years ago when the human lineage broke away from that of chimpanzees.

Over time, an ensemble cast of over 20 early humans species, or hominids, came to the fore.

Most became extinct while others might have been ancestors to today's humans.

Each species exhibited varying degrees of human-like physical and behavioral traits such as large brains, small teeth, bipedality, and tool use.

These hominins fell into three major groups:

Early hominins, australopithecines, and homo genus.

Humanity's earliest relatives lived between seven and 4.4 million years ago in Africa.

Having most recently shared a common ancestor with chimpanzees, they had many ape-like traits such as a small cranial capacity.

However fossils show that some ancient hominins were also beginning to show human-like characteristics, such as small canines that were likely used more for eating and not for hunting or fighting.

The next phase of hominid evolution involved primates called australopithecines.

They lived between 4.4 and 1.4 million years ago across the African continent.

Like their ancient brethren, australopithecines had some ape-like traits.

However, changes in the skull, spine and legs indicate a notable shift toward a very human-like trait:

Consistent bipedal locomotion.

The third and current phase of human evolution involves members of the genus homo.

The earliest homo species likely date to more than two million years ago, making them a contemporary of some australopithecines.

But unlike earlier hominins who exhibited a mosaic of ape and human-like traits, Homo species were becoming distinctly more human.

Their cranial capacity was growing larger than any other hominins.

They developed sophisticated stone tool technology, and they became the first to control fire.

These physical and behavioral adaptations, along with advancements in technology, allowed some homo species to be the first to migrate out of Africa and explore the rest of the world.

While a cast of over 20 hominin species have walked this Earth, only one remains.

Homo sapiens shaped by millions of years of evolution embarked on a journey of exploration and industry its ancestors could have only dreamed.