Within the span of one human lifetime, or even a few human lifetimes, it may see

Question

Within the span of one human lifetime, or even a few human lifetimes, it may seem as if things have always been relatively the same. For example, most deserts and forests that are around today have been around for as long as people can remember, and the species of organisms that live in them are also familiar. At first glance, it seems as if humans are to blame for the changes that do occur; for example, when humans change the landscape or drive a spedies to extinction. In reality, the structure of the blosphere has been changing for as long as it has existed. Most changes occurred long before humans showed up on the planet. While scientists do not necessarily know what all of those changes were, there are clues scattered around Earth pointing to the fact that the biosphere-and the organisms within it-have changed over time. Some of the best evidence that species have changed over time is the presence of vestigial body parts. Vestigial body parts are structures in a living organism that do not actively contribute to its life but are likely the remains of structures from the organism's ancestors. Growing such useless structures costs the organism energy and nutrients, so an organism would have the genes to grow such a structure only if that structure had been useful to its ancestors that passed on those genes. Thus, the fact that the organism has a structure that it does not use is an indication that the species has changed over time. Which of the following images is not an example of a vestigial structure? O Steve Satushek/ Workbook Stock/ Getty Images Science Photo Library/ Getty Images Roger Tidman/NHPA/ Photoshot/ Newscom The large and colorful tails of peacocks The coccyx, or tailbone, in humans The underdeveloped, skin-covered eyes of blind mole rats

Explanation / Answer

The organs which are no longer in use but are present in the body since our ancestors had them are termed as Vestigial organs. For example, Appendix, Coccyx, etc. are vestigial to humans.

Our ancestors used to have a tail and hence it is a remnant of our ancestors. Similarly, the blind mole rat has tiny eyes completely covered by layers of skin. They are vestigial organs in comparison to the functional eyes of the rat,s ancient ancestors.

But peacock tail is not vestigial organ as they are still in use.

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