Evolutionary developmental biology facts for kids
Evolutionary developmental biology is a cool science field. It looks at how living things grow and develop, and how these processes have changed over time. For short, it's often called 'evo-devo.
This field combines ideas from evolution (how species change) and developmental biology (how a single organism grows from a tiny egg to an adult). It helps us understand why animals look the way they do and how new body features appear.
In 1859, Charles Darwin wrote his famous book, The Origin of Species. He explained his idea of natural selection, which is how species evolve. Darwin knew that how an animal develops from an embryo was super important for understanding evolution. He said that features from an embryo are just as important as features from an adult.
Later, in 1866, Ernst Haeckel had an idea. He thought that an embryo's development (called ontogeny) repeated the entire evolutionary history of its species (called phylogeny). For example, he thought human embryos had gill slits and tails because our ancient ancestors had them. While this idea was interesting, scientists have since found that it's mostly wrong.
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How Evo-Devo Grew
After the 1930s, scientists became very interested again in how development and evolution are linked. This was around the time of the modern evolutionary synthesis, which combined Darwin's ideas with genetics.
Gavin de Beer's Ideas
A scientist named Gavin de Beer wrote a book in 1930 called Embryos and Evolution. He talked a lot about something called heterochrony. This means changes in the timing or speed of development. One important type of heterochrony is paedomorphosis.
Paedomorphosis happens when an adult animal keeps features that were only seen in its young (juvenile) form. De Beer thought this was important for evolution. Why? Because young tissues are more flexible and can change more easily. Tissues that are already very specialized are harder to change.
De Beer also came up with the idea of clandestine evolution. This helped explain why the fossil record sometimes shows sudden changes. Darwin's theory suggested evolution was usually very slow and gradual.
Imagine a new feature slowly developing in a young animal. If this animal stayed in its young form when it became an adult (this is called neoteny), then the new feature would suddenly appear in the fossil record. Even though it evolved slowly, it would look like a sudden jump.
Stephen Jay Gould, another famous scientist, said that de Beer's book was very important. It helped bring the study of embryos into the main ideas of evolution.
Humans and Neoteny
Many scientists think that humans show signs of neoteny. This means that adult humans have some features that are more like young great apes than adult great apes.
Here are some features that suggest humans are neotenous:
- A flatter and wider face
- A larger brain
- Less body hair
- A smaller nose
- Smaller teeth and jaws
- Thinner skull bones
- Legs that are longer than arms
- Larger eyes
- An upright way of standing
Even more interesting is how humans keep learning and playing into adulthood. Most other mammals, including apes, only show this kind of behavior when they are young. This suggests that our brains act more like young apes than adult apes in some ways.
Genes and Evo-Devo
Modern evo-devo really took off when scientists found clear proof that special genes control development. These genes are called hox genes.
E.B. Lewis's Discovery
Edward B. Lewis did many experiments with fruit flies (called Drosophila). He found a group of genes that control how the fly's body parts develop. These genes make proteins that turn other genes on or off. This process guides the final shape of the organism.
What's amazing is that the order of these control genes on the chromosome matches the order in which they affect body parts. This is called co-linearity. Even more, this group of master control genes helps program the development of almost all higher animals!
Each of these genes contains a special part called a homeobox. This is a piece of DNA that is incredibly similar in many different animals, even very different ones. This suggests that these important control genes came from a single original gene that was copied many times. Lewis believed that by comparing these control genes across the animal kingdom, we could understand how both organisms and their genes have evolved.
In recent years, many science journals have dedicated special issues to evo-devo. This shows how important and exciting this field has become!
Images for kids
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A gene regulatory network is like a complex map of how genes interact to control development.
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Some centipedes, like the Geophilomorpha, always have an odd number of body segments, from 27 to 191. This shows how development can be very specific.
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See also
In Spanish: Biología evolutiva del desarrollo para niños
