explain how homologous structures provide evidence of common ancestry (detailed explanation)
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Homologous features
If two or more species share a unique physical feature, such as a complex bone structure or a body plan, they may all have inherited this feature from a common ancestor. Physical features shared due to evolutionary history (a common ancestor) are said to be homologous.
To give one classic example, the forelimbs of whales, humans, birds, and dogs look pretty different on the outside. That's because they're adapted to function in different environments. However, if you look at the bone structure of the forelimbs, you'll find that the pattern of bones is very similar across species. It's unlikely that such similar structures would have evolved independently in each species, and more likely that the basic layout of bones was already present in a common ancestor of whales, humans, dogs, and birds.
The similar bone arrangement of the human, bird, and whale forelimb is a structural homology. Structural homologies indicate a shared common ancestor.
Some homologous structures can be seen only in embryos. For instance, all vertebrate embryos (including humans) have gill slits and a tail during early development. The developmental patterns of these species become more different later on (which is why your embryonic tail is now your tailbone, and your gill slits have turned into your jaw and inner ear)^22. Homologous embryonic structures reflect that the developmental programs of vertebrates are variations on a similar plan that existed in their last common ancestor.
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Homologous features
If two or more species share a unique physical feature, such as a complex bone structure or a body plan, they may all have inherited this feature from a common ancestor. Physical features shared due to evolutionary history (a common ancestor) are said to be homologous.
To give one classic example, the forelimbs of whales, humans, birds, and dogs look pretty different on the outside. That's because they're adapted to function in different environments. However, if you look at the bone structure of the forelimbs, you'll find that the pattern of bones is very similar across species. It's unlikely that such similar structures would have evolved independently in each species, and more likely that the basic layout of bones was already present in a common ancestor of whales, humans, dogs, and birds.
The similar bone arrangement of the human, bird, and whale forelimb is a structural homology. Structural homologies indicate a shared common ancestor.
Some homologous structures can be seen only in embryos. For instance, all vertebrate embryos (including humans) have gill slits and a tail during early development. The developmental patterns of these species become more different later on (which is why your embryonic tail is now your tailbone, and your gill slits have turned into your jaw and inner ear)^22. Homologous embryonic structures reflect that the developmental programs of vertebrates are variations on a similar plan that existed in their last common ancestor.
Hope it helps.
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✔️explain how homologous structures provide evidence of common ancestry.
➡️ANSWER:
=>In mammals we see extremely similar bone structures in the forelegs (also in other parts of the body but we are looking at this image here for this example). The evidence of homology or common descent lies in the idea that these animals either have a common ancestor with this similar bone structure and it was just modified through evolution over time for the different purposes they serve, such as bats flying, whales swimming and cats slapping you in the face.
The alternative hypothesis is that all mammals went through convergent evolution, or evolved separately to meet these extremely similar phenotypes coincidentally which is highly unlikely.
Hope this helps.
➡️ANSWER:
=>In mammals we see extremely similar bone structures in the forelegs (also in other parts of the body but we are looking at this image here for this example). The evidence of homology or common descent lies in the idea that these animals either have a common ancestor with this similar bone structure and it was just modified through evolution over time for the different purposes they serve, such as bats flying, whales swimming and cats slapping you in the face.
The alternative hypothesis is that all mammals went through convergent evolution, or evolved separately to meet these extremely similar phenotypes coincidentally which is highly unlikely.
Hope this helps.
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