Modern Human

Associated Smithsonian Expert: Kari Bruwelheide, M.A.

Kari Bruwelheide examines the inside of an iron coffin with fellow Smithsonian researchers.

Photo by Smithsonian Institution

Kari Bruwelheide is a physical anthropologist at the Smithsonian National Museum of Natural History where she studies human bones, including skeletons from the distant past and more recent remains involved in criminal cases. She stumbled upon her career path by accident when she volunteered on a project during her undergraduate studies. Much of her current research in bioarchaeology, skeletal biology, and forensic anthropology is focused on the early colonial period in the Americas. Favorite parts of her job are that each day presents a new mystery and a new person to meet and learn about on a personal level, and the ability to give closure to families of victims of criminal cases. Although she's learned about so many people, the one that’s had a large impact on her was a young boy who died at historic Jamestown, Va. His incredible story makes the past real and relevant to people, especially younger people who are rarely represented in historical writings or documents. Kari received her bachelor's degree in English and Anthropology from Luther College in Iowa and a master's degree in Physical Anthropology from the University of Nebraska, Lincoln.

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Two fossil teeth (incisors) and two stone tools from Yuanmou, China
Photo by Smithsonian Institution

Homo sapiens

Both Prehistoric and modern humans are scientifically known as Homo sapiens. They are members of the primate family. They share many traits with their most closely related relatives, the living great apes, but are not directly descended from them. First appearing in Africa roughly 200,000 years ago, they spread to Europe, Asia, and Australia by about 40,000 years ago. Some of the earliest fossils of our species were found in 1868 at the site of Cro-Magnon in France. Homo sapiens have flat faces, reduced brow ridges (the area above the eyes), and very large brain cases. Their large brains allow them to interact with their surroundings and each other in ways that other animals and species of Homo could not. Unlike their ancestors, Homo sapiens have complex social networks and languages, art, specialized tools, and have learned to change and control their environment to benefit themselves. They continue to adapt and survive throughout the world today.

This bear leg shows how similar humans bones are to animal bones.
Photo by Smithsonian Institution

Human Bones versus Animal Bones

Humans are part of a group of organisms that have endoskeletons, or bones that are under their skin. Many non-human animals have bones that look like and serve functions similar to those of human bones. Sometimes people find bones and think they are human. In order to determine whether bones are human or non-human, they are examined by anthropologists. Forensic and physical anthropologists look at the bones' size, proportion, shape, and internal structure. In the case of human bones, for example, the pelvis is designed for walking on two legs, so the spine has a distinctive S-curve to support an upright body. Likewise, human hands and feet have also evolved to have distinctive forms.

Forensic anthropologists use an osteometric board to measure long bones to determine height.
Photo by Smithsonian Institution

Using Long Bones to Determine Height

The human leg is made up of four major bones that connect the pelvis to the feet. These include the patella (knee cap), and the three long bones: the femur (thigh bone), the tibia (shin bone), and the fibula (lower leg bone). Forensic anthropologists can use these bones to collect different types of information about a person. One thing they can learn is how tall a person may have been when they were alive. To do this, they measure the long bones using specialized tools and compare the results to a database that contains the measurements of bones from individuals of known stature. Mathematical formulas have also been created to calculate stature using the maximum lengths of specific long bones. Although this will not produce an exact measurement of the person, it will give the anthropologists a narrow range that is considered to be trustworthy. While all of the long bones of the body can be used in such analysis, the bones of the leg produce the best results.


Adaptation of Human Ancestors

Evolution occurs when a species adapts and changes over time through descent with modification. This is based on selective pressures within their environment. Human evolution is no different. Early humans walked on four legs, ate mostly plants, and had small brains. Over millions of years, they adapted to take advantage of the world around them. For example, they began to walk upright on two legs, became predators and skilled hunters, and developed large brains that allowed for sophisticated communication, a higher degree of forethought and planning, complex social interactions, and other traits that define them as a species. Often these adaptations were in response to a change in their environment, such as temperature change in the beginning or ending of an ice age or when a new species of predator moved into the area. Like all species, modern humans continue to change today and further adapt to their environment.