Human biology

Scientists study how the human body works. They look at how we grow and change.

We have many parts that help us. We use our lungs to breathe air. This air gives us energy to move.

Our bodies also need special food. We need vitamins to stay well. We can even make a vitamin from sunlight.

Humans have very large brains. This helps us use tools and talk. We also walk on two legs.

Learning about our bodies helps us stay healthy. It helps doctors help us live long lives.

Human biology is the study of how people work. It looks at many things. Scientists study our genes and how we grow. They also look at how we live in groups. A man named Raymond Pearl helped make this a special field. He started a journal about it in 1929.

Most of our body parts are like other mammals. We have a skeleton and a nervous system. We use our lungs to breathe in oxygen. This helps us make power to move. We also have an immune system. This helps protect us from disease.

Humans have some special traits. We have very large brains. This helps us use tools and speak. We also walk on two legs. Most other animals do not do this. Humans also live a long time. We have a very long childhood. It takes 12 to 16 years to grow up. We also have very little hair on our skin. This lets us make Vitamin D3 from the sun. This vitamin helps our bodies stay well.

Human biology is a big field of study. It looks at how people work as living things. Scientists use many different tools to learn about us. They study our genes and how our bodies grow. They also look at how we live in groups. This study connects many areas like anatomy and nutrition. It helps us understand our place in the world.

Our bodies work in many amazing ways. We have an internal skeleton to hold us up. A nervous system sends information to our brain. We breathe air into our lungs to get oxygen. This oxygen helps our bodies make energy. We also have an immune system to fight disease. Most of these parts are like other mammals.

This science became its own subject in the 20th century. A man named Raymond Pearl helped start it. He was a professor at Johns Hopkins University. Pearl founded the journal Human Biology in 1929. He studied how people grow and live long lives. Other experts like Franz Boas also did important work. They studied how people change in different places.

Humans have some very special traits. We have very large brains for our size. This helps us use tools and speak languages. We also walk on two legs most of the time. This upright stance changed our skeleton. Humans also live a long time. In the developed world, people live nearly 80 years. We also have the longest childhood of any mammal.

What we eat is also a key part of our biology. We need fats, proteins, and vitamins to stay well. Humans need Vitamin C to avoid getting sick. We can also make Vitamin D3 from sunlight. Our skin uses UV light to make this vitamin. This is easier because humans have very little hair. We also live with many tiny living things. These tiny organisms live on our skin and in our guts.

Human biology is an interdisciplinary field of study. It examines humans through the interplay of many diverse scientific areas. These include genetics, evolution, physiology, anatomy, and ecology. It also looks at nutrition, anthropology, and sociocultural influences. This science is closely related to the biomedical sciences. It also connects to biological anthropology. By studying these different fields, researchers understand how humans function as living organisms. Human biology serves as the essential knowledge base for the field of medicine.

To understand how humans work, we must look at our biological systems. Like most mammals, humans possess several core systems. We have an internal skeleton for support and a circulatory system to move blood. A nervous system provides sensory information and coordinates our muscular activity. Our respiratory system involves inhaling air into the lungs to use oxygen for energy. We also use an endocrine system to produce and eliminate hormones. These hormones act as biochemical signaling agents throughout the body. Finally, an immune system works to protect us against disease.

While many systems are similar to other mammals, humans have unique attributes. Our most notable feature is a very large brain relative to our head size. This large brain allows for complex languages and the use of intricate tools. Humans also rely almost exclusively on bipedal locomotion, which is walking upright on two legs. This upright stance caused significant changes in our skeleton. Specifically, it changed the way the pelvis and femur connect. It also changed how the head is articulated with the body. Unlike many other mammals, humans have very little body hair. This leaves us almost naked, which is a trait that scientists still debate.

Human biology emerged as a distinct scientific discipline in the early 20th century. Before this, studies were often focused strictly on anatomy. In the 1920s, scientists began applying Charles Darwin’s theories of evolution to human populations. This allowed for a more comprehensive understanding of human adaptation. Raymond Pearl was a major figure in this movement. He was a biologist and a professor at Johns Hopkins University. In 1929, Pearl founded the journal *Human Biology*. His work helped establish the field as a separate subsection of biology. He explored many topics, including fertility, growth, and the biology of longevity.

Other important figures shaped the study of physical anthropology during this time. Franz Boas was a key researcher who emphasized population analyses. He challenged older ideas about fixed racial types by studying how the environment affects biological variation. Aleš Hrdlička also played a vital role. In 1918, he founded the *American Journal of Physical Anthropology*. He also established the American Association of Physical Anthropologists in 1930. His work focused on standardizing research methods and data collection. These efforts made comparative studies much more reliable for scientists.

Human nutrition and metabolism follow specific biological requirements. We are omnivores, meaning we require a balanced intake of carbohydrates, fats, proteins, vitamins, and minerals. However, humans have very specific needs for certain nutrients. We must consume two specific amino acids: alpha-linolenic acid and linoleic acid. Without these, human life is not sustainable in the long term. We also have a unique relationship with Vitamin D3. Humans can synthesize Vitamin D3 using natural UV light from the sun on the skin. Because we have very little hair, our skin is exposed to this light. Interestingly, darker skin can manufacture less Vitamin D3 in this way.

Finally, human biology includes the study of other organisms that live with us. We host a vast array of life, ranging from parasitic insects like fleas to bacterial pathogens. Many of these organisms make up our specialized biome. This includes the biotic flora found on our skin and in our nasal regions. We also have a complex biome in our large intestine. These microscopic assemblages help protect us from harm and assist in digestion. Recent studies show these organisms may even have complex effects on our mood and well-being. This interconnectedness shows that human biology is not just about the human body alone.