Nav: Home

The history of humanity in your face

April 15, 2019

The face you see in the mirror is the result of millions of years of evolution and reflects the most distinctive features that we use to identify and recognize each other, molded by our need to eat, breath, see, and communicate.

But how did the modern human face evolve to look the way it does? Eight of the top experts on the evolution of the human face, including Arizona State University's William Kimbel, collaborated on an article published this week in the journal Nature Ecology & Evolution to tell this four-million-year story. Kimbel is the director of the Institute of Human Origins and Virginia M. Ullman Professor of Natural History and the Environment in the School of Human Evolution and Social Change.

After our ancestors stood on two legs and began to walk upright, at least 4.5 million years ago, the skeletal framework of a bipedal creature was pretty well formed. Limbs and digits became longer or shorter, but the functional architecture of bipedal locomotion had developed.

But the skull and teeth provide a rich library of changes that we can track over time, describing the history of evolution of our species. Prime factors in the changing structure of the face include a growing brain and adaptations to respiratory and energy demands, but most importantly, changes in the jaw, teeth, and face responded to shifts in diet and feeding behavior. We are, or we evolved to be, what we eat--literally!

Diet has played a large role in explaining evolutionary changes in facial shape. The earliest human ancestors ate tough plant foods that required large jaw muscles and cheek teeth to break down, and their faces were correspondingly broad and deep, with massive muscle attachment areas.

As the environment changed to drier, less wooded conditions, especially in the last two million years, early Homo species began to routinely use tools to break down foods or cut meat. The jaws and teeth changed to meet a less demanding food source, and the face became more delicate, with a flatter countenance.

Changes in the human face may not be due only to purely mechanical factors. The human face, after all, plays an important role in social interaction, emotion, and communication. Some of these changes may be driven, in part, by social context. Our ancestors were challenged by the environment and increasingly impacted by culture and social factors. Over time, the ability to form diverse facial expressions likely enhanced nonverbal communication.

Large, protruding brow ridges are typical of some extinct species of our own genus, Homo, like Homo erectus and the Neanderthals. What function did these structures play in adaptive changes in the face? The African great apes also have strong brow ridges, which researchers suggest help to communicate dominance or aggression. It is probably safe to conclude that similar social functions influenced the facial form of our ancestors and extinct relatives. Along with large, sharp canine teeth, large brow ridges were lost along the evolutionary road to our own species, perhaps as we evolved to become less aggressive and more cooperative in social contexts.

"We are a product of our past," says Kimbel. "Understanding the process by which we became human entitles us to look at our own anatomy with wonder and to ask what different parts of our anatomy tell us about the historical pathway to modernity."
-end-


Arizona State University

Related Evolution Articles:

An evolution in the understanding of evolution
In an open-source research paper, a UVA Engineering professor and her former Ph.D. student share a new, more accurate method for modeling evolutionary change.
Chemical evolution -- One-pot wonder
Before life, there was RNA: Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich show how the four different letters of this genetic alphabet could be created from simple precursor molecules on early Earth -- under the same environmental conditions.
Catching evolution in the act
Researchers have produced some of the first evidence that shows that artificial selection and natural selection act on the same genes, a hypothesis predicted by Charles Darwin in 1859.
Guppies teach us why evolution happens
New study on guppies shows that animals evolve in response the the environment they create in the absence of predators, rather than in response to the risk of being eaten.
Undercover evolution
Our individuality is encrypted in our DNA, but it is deeper than expected.
Evolution designed by parasites
In 'Invisible Designers: Brain Evolution Through the Lens of Parasite Manipulation,' published in the September 2019 issue of The Quarterly Review of Biology, Marco Del Giudice explores an overlooked aspect of the relationship between parasites and their hosts by systematically discussing the ways in which parasitic behavior manipulation may encourage the evolution of mechanisms in the host's nervous and endocrine systems.
Tracing the evolution of vision
The function of the visual photopigment rhodopsin and its action in the retina to facilitate vision is well understood.
Directed evolution comes to plants
Accelerating plant evolution with CRISPR paves the way for breeders to engineer new crop varieties.
Pain free, thanks to evolution
African mole-rats are insensitive to many different kinds of pain.
Evolution in the gut
Evolution and dietary habits interact and determine the composition of bacteria in the digestive tract.
More Evolution News and Evolution Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.