Ask A Scientist

Do all animals have brains? 

Asked by: Garrett Kreeger
School: St. James School, Johnson City
Grade: 6

Hobbies/Interests: Meteorology
Career Interest: Pro basketball player

Answer from Douglas W. Green, EdD

Adjunct Lecturer, Binghamton University

Other: Former principal at Woodrow Wilson Elementary in Binghamton, NY
Research area: Leadership, Learning Theory and Social Media
Interests/hobbies: Playing my banjo, biking, golf and reading
Family: Daughter Lena, age 29, who works for the Teen Nickelodeon channel in Times Square, New York City.  

The answer is no, but we first have to define animal and brain. Animals are living creatures that unlike plants cannot produce food internally. They must eat plants and/or each other. Most animals also are motile, which means they move about. The brain is an organ that serves as the center of an animal's nervous system. All animals with backbones (vertebrates) and most animals without backbones (invertebrates) have one. Some invertebrates like sponges, jellyfish, and starfish lack this organ, and are indeed brainless. So even though almost all animals have a brain, the brains vary a great deal from one species to another. If you buy the theory of evolution, the first brain evolved about 600 million years ago in primitive worm. If you want an idea of what that looked like, dissect an earthworm. This is a common activity in biology classes.

As evolution continued, animals got bigger more complex and so did their brains. Compared to human brains, amphibian, reptile, and bird brains were pretty simple. The center of our brains, however, are much like the brains of these primitive animals as it controls basics like breathing and balance. As mammals evolved, their brains added an outer layer called the cortex. Mammals called primates featuring monkeys and apes came next with still larger brains.

Modern humans showed up about 200,000 years ago with brains about as large as we have today. Unlike other animals, our brain can think, plan, and create new things. It has long-term memory, which is rather large, and a short-term memory that holds maybe five to seven things at a time. When you are trying to solve a problem or create something, you use your long-term memory that you can access quickly along with information from your environment, which today includes the Internet. Memorizing information may not be fun, but it's very useful. Scientists are just scratching the surface when it comes to understanding how brains work. We do know that exercise improves brain function as does a good night's sleep. Also, any kind of stress interferes with thinking. If your head takes a hit, the brain can bounce off your skull and give you a concussion. As we learn more about brain injuries, we become more wary of sports like football where concussions are common. Read my summary of "Brain Rules" if you want to learn more. http://bit.ly/17VKh6o

Last Updated: 9/18/13