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For example, a sperm swims faster if it's carrying the genetic material that would result in a tall person and in the comments It seems to me that there would have to be some defined standard of a normal DNA that the sperm would check against to determine how "broken" it is, and I doubt there's something like that If some aspects of sperm ...


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First of all, I should quote the sentence from the MOST reliable ophthalmology sourcing in the world - American Academy of Ophthalmology: Section 11 - "Lens and Cataract" "The equatorial diameter of the unfixed human lens measures 2 mm at 12 weeks and 6 mm at 35 weeks. Both the growth and the maturation of lenticular fibers continue throughout life." The ...


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Shigeta, you have some good points there. I wanted to clarify some things. Sperm and ova are considered tissues, not individual living creatures. They are not individually capable of cell division nor production of offspring. They are specialized cells with specific functions that are created by a multicellular organism as a means of transferring DNA. ...


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With age your eyeball, as everything else in your body with time, actually shrinks. In the developing stages I'm not sure when it reaches its full size though. So this is why elder often report far sightedness, when they need reading glasses. This is because the image no longer falls on the retina perfectly. When you are near sighted your eye is actually too ...


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I think there is a strong driving force for sperm to be free living haploid versions of human beings. Since they are a product of meiosis sperm are the product of recombination of both the male chromosome sets. While I'm sure that if we look closely enough, the germline cells that produce the sperm are contributing some protein and structure to the sperm, ...


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No. In fact the lens of the eye, which is nearly optically perfect in humans, does not change or grow after it is fully formed around week 26 of gestation. Interestingly this is why one of the cues for identifying young children is having small faces with large eyes. This also the case for puppies and cats and other animals, who are mostly cuter when they ...


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Human females have one of the worst chidbirth experiences. This is because of our extremely high cranial capacity compared to the apes. This had an obvious evolutionary advantage and made us what we are today. However this creates problems as the braincase has to pass the pelvic cavity during childbirth. The wider hips in women compensate for this but still ...


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That's an interesting question. And it is also a common misunderstanding of evolutionary processes. Thanks to @Chris comment, we know/can assume that high mortality rate is not a consequence of industrialization but has ever been before the era of modern medicine. Women don't let themselves die in order to improve the species. Those women that carry the ...


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In short; yes. It depends on the breed (not all lay up to 1 egg/day), the age of the bird and on nutrition. High yielding breeds of chicken are e.g. dependent on supplements of calcium to be able to produce new shells rapidly (e.g. in the form of ground-up shells). Some information on the nutrient requirements of chicken can be found at Feeding the Laying ...


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I'm not at a biologist, but I have a pet theory I'd like to throw into the ring: hermaphroditism tends to be unstable in a similar way to strong sex skews. Imagine species A where 90% of offspring are female; at moderate population density, the 10% male population will be more than sufficient to maintain the females, and having 90% of the population able to ...


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Richard Dawkins dedicated a part of his magnificent The Selfish Gene to explain the evolution of macro- and micro-gametes. It's worth the read.



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