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122 votes
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Are male and female brains physically different from birth?

Short answer Yes, men and women's brains are different before birth. Background First off, learning effects versus genetic differences is the familiar nature versus nurture issue. Several genes on ...
AliceD's user avatar
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67 votes
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How does a baby deer stand the day it's born?

If you compare placental mammals in how much time they need to start walking, you'll see that deer are no exception. Humans are an exception. Hypothesis of Obstetrical Dilemma The hypothesis of ...
Remi.b's user avatar
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40 votes
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How long before robin no longer needs the nest on my porch?

According to Cornell's All About Birds website, you will have to wait about a month for the nest to be cleared. The egg incubation period is 12–14 days. Following hatching, the nestlings will remain ...
theforestecologist's user avatar
34 votes

How does a baby deer stand the day it's born?

Deer are hardly unique in this, The young of horses, cows, and I suspect most grazing species are able to walk soon after birth. The reason, of course, is evolutionary: flight is the species ...
jamesqf's user avatar
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24 votes
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Is female the default sex in humans?

Summary: The idea that primary sexual determination defaults to female was proposed several decades ago and is primarily based on the observation that, in the absence of Sry, ovarian development ...
canadianer's user avatar
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18 votes

Have elephants (or any species other than humans) been known to cover their dead?

Yes. I was able to find a book1 (see p. 237-239) and a paper2 (I couldn't access this one) suggesting elephants bury their dead and other animals in African elephants (Loxodonta africana). I also ...
bob1's user avatar
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9 votes

How does a baby deer stand the day it's born?

That you use the word "learn" in your question leads me to think that you're under a common misconception that people have about biology. It can seem self-evident to us that certain skills, for ...
user151841's user avatar
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8 votes
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How do neurons find each other?

Q: We know neurons can organize into very complex networks, but how? The answer is your first guess: Neurons find other target neurons with specific chemical signals. Q: What are the names of said ...
leekaiinthesky's user avatar
8 votes

Are male and female brains physically different from birth?

One point of view you rarely see is the perspective of sex differences from an evolutionary standpoint. Never mind that this is the reason why the differences exist in the first place if they do at ...
Tyler S. Loeper's user avatar
8 votes
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What animal has the longest juvenile period?

As you indicate in your question, the average age of sexual maturity is probably the best way to approach this, since immaturity is usually how juveniles are defined. Age of puberty is also different ...
fileunderwater's user avatar
8 votes
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Are there any known consequences of the right-handedness of the DNA double helix?

The short answer is no, there currently aren't any visible macroscopic asymmetries in some organisms traceable to DNA's handedness. The long answer is still no, but I want to clarify that this "no" ...
Sage W.'s user avatar
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7 votes
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What does a female mosquito need from blood?

According to the Introduction to this paper: Attractiveness to biting insects is important in medical contexts, mostly in the dynamics of transmission of pathogens by mosquitoes that cause diseases ...
Alan Boyd's user avatar
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7 votes
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Why do Centipedes always have an odd number of pairs of legs?

Centipedes are part of the group of insects that utilize a short germ-band mode of embryonic development.1 One feature of this type of segmentation is that new segments are added sequentially to the ...
acvill's user avatar
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7 votes

Spontaneous generation of fruit flies

Regarding spontaneous generation: Francesco Redi performed an experiment 350 years ago disproving spontaneous generation of insects (see here). Source: Lumen Learning Further work by Louis Pasteur ...
theforestecologist's user avatar
6 votes

What's the determinant of the male-biased birth sex ratio in humans?

There are a number of ways in which the true sex-ratio at birth (let's assume the 51:49 is well estimated and is the true ratio) could deviate from 50:50. This list is just an brief overview. Sex, in ...
rg255's user avatar
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6 votes

What happens to the language processing brain part if no language is ever learned?

Although this specific experiment wouldn't be done, similar experiments have been done in experiments in animal models where a sensory input is removed/altered. These experiments show that if you ...
Bryan Krause's user avatar
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6 votes

Larval abalone devlopmental times - what does ~ °C.days or °C hr-1 mean

From e.g. Fukazawa, H., Kawamura, T., Takami, H., & Watanabe, Y. (2007). Oogenesis and relevant changes in egg quality of abalone Haliotis discus hannai during a single spawning season. ...
Bryan Krause's user avatar
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5 votes

Do patella bones form in people born with the inability to walk?

In mice, patella would form, but not separate from femur. On the development of the patella: Previous studies have suggested a central role for mechanical load in the initiation of sesamoid ...
KaPy3141's user avatar
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5 votes

Butterfly wings with ragged edges - worn out, camouflage, fungus, or something else?

In both these cases, the butterflies are old (relatively speaking) and worn. Usually, adult butterflies only live during a specific season (which usually can last weeks to months) or with several ...
fileunderwater's user avatar
4 votes
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What happens to the hollow nerve cord?

The "hollow" i.e. the neural canal develops into the ventricles, the cerebral aqueduct and the spinal canal (Wikipedia; also see this site). For a more authoritative reference, see this book by ...
WYSIWYG's user avatar
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4 votes
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Spermatogenesis in humans - timing of phases and chromatin modifications

Spermatogenesis (Beginning to end): 64 +- 8 days (range 42 to 76) There is considerable individual variation. This includes time in epididymis. Amann 2008 argue ...
Calen's user avatar
  • 191
4 votes
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What is the evolutionary advantage of menstruation?

Human female ovaries only have a certain number of ova; none are manufactured in adulthood. Once they're gone (that's when menopause occurs), they're gone. You can also ask, why did evolution result ...
anongoodnurse's user avatar
4 votes
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Why aren't human babies considered larvae?

For animals with a clear larval stage, the presence of such a stage indicates that there is a metamorphosis, a change in body morphology at some point in development. Metamorphosis does not ...
Bryan Krause's user avatar
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4 votes
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How do schistosomes find and attach to human skin?

Schistosoma recognize human skin by mechanical, thermal and chemical stimuli from host. Attachment of parasite to skin is stimulated by L-arginine. Schistosomes specifically bind to L -argine by ...
Twinkle Sheen's user avatar
4 votes

Why can human viruses that can't infect chickens be grown in embryonic chicken cells?

The measles vaccine uses an attenuated virus: one that has been modified to reduce virulence such that it is (hopefully) no longer harmful to the host but still retains the antigenic determinants to ...
canadianer's user avatar
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4 votes
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Do we know the genome contains all the information necessary for embryonic development?

The second quote is about stochastically determining which side is the "head" and which is the "tail", effectively, which occurs by positive feedback of an existing gradient. This ...
Bryan Krause's user avatar
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3 votes
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What is cytoplasmic localization?

"Cytoplasmic localization" is a very general term and it means that something is present in the cytoplasm. For instance (hypothetical but there are known examples), you can say protein-X is localized ...
WYSIWYG's user avatar
  • 35.6k
3 votes

Why do bananas grow curved?

The "proximate cause" would be a differential rate of growth on the different sides of the individual bananas. If the cells on the underside of the banana are dividing faster than those on the top, ...
Jenn D.'s user avatar
  • 169

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