The body hair of all mammals automatically stands up when cold, creating a fluffy layer of warmth. When we’re cold, the muscles around the hair follicles contract – a reflex left over from when our ancestors had long body hair. But since we don’t have much body hair, all we see are the goose bumps on our skin.
Human Characteristics: What Does it Mean to be Human?
Part of what it means to be human is how we became human. Over a long period of time, as early humans adapted to a changing world, they evolved certain characteristics that help define our species today.
This section of our website focuses on several human characteristics that evolved over the past 6 million years. As you explore the scientific evidence for these characteristics, you will discover that these traits did not emerge all at once or in any one species. There were important milestones along the way. For example, early humans began walking upright before they began making tools. A rapid increase in brain size occurred before early humans began using symbols to communicate. And all of these traits emerged before humans began domesticating plants and animals.