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Fossils Reveal the Story of Our Relatives
In the 8 million years or so since the earliest ancestors of
humans diverged from the apes, at least a dozen humanlike species, called hominids,
have lived on Earth. And this list is getting longer. As scientists discover new
fossils, the hominid family tree grows new branches.
But fossils are often difficult to categorize neatly as one
species or another. Like all creatures, no two individual hominids were alike.
And over the millions of years most of the species existed, hominids changed;
they evolved; some diverged and became new species.
This is the story of our distant relatives, as told by the
fossil record.
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The Hominid Family Tree
At first glance, it seems there are far more questions than
answers regarding the relationships among species on the hominid family tree.
The graphic above plots 15 different species along a timeline spanning 6 million
years, and it depicts, with connecting lines, how some scientists think these
species relate to one another. A few relationships are clear. For instance, there
is consensus among scientists that the three most recent species of hominids
(Homo heidelbergensis, Homo neanderthalensis, and modern humans,
Homo sapiens) all evolved from an earlier species called Homo erectus.
But other relationships are murkier.
Indeed, our view of the origins of humankind is incomplete,
and the search for pieces to the puzzle continues. But to view the question marks
on the hominid family tree merely as gaps in our knowledge belies the reality of
evolution. Hominid species were changing over periods of hundreds of thousands of
years, adapting to new environmental conditions. And so, given that the present
fossil record gives us only a glimpse of these evolving species, it's very difficult
-- even unnatural -- to identify exactly when a species "became" something else.
In order to begin to understand human evolution, however,
scientists have had to take the fossils they have, analyze them, and categorize
them based on similarities and differences. In this way, they are able to find
trends among the species and a better understanding of how they came to be. In
this way they have allowed us a glimpse into our ancient past -- a glimpse that
will undoubtedly become clearer in years to come.
-> Learn about the fossilized evidence of our fellow hominids
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