122
votes
Accepted
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 ...
- 52.3k
68
votes
Accepted
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 ...
- 68k
40
votes
Accepted
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 ...
- 29.7k
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 ...
- 3,633
24
votes
Accepted
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 ...
- 17.7k
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 ...
- 11.2k
15
votes
Why does a fetus drink and urinate into the amniotic fluid?
In utero, the growing little human is getting ready to be an independently functioning individual. While it is everything but that, it must be able to obtain fluids and nutrients through its mother's ...
- 52.3k
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 ...
- 1,387
8
votes
Accepted
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 ...
- 445
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 ...
- 181
8
votes
Accepted
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 ...
- 16.7k
8
votes
Accepted
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" ...
- 96
7
votes
Accepted
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 ...
- 22.7k
7
votes
Accepted
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 ...
- 8,276
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 ...
- 29.7k
6
votes
Accepted
How may the age of a child be estimated when required to do so, in video-graphic evidence?
In short, without direct physical evidence (forensic or medical examination), testimony, or documentation to act as proof, you are left up to the discretion of the court to determine whether evidence ...
- 4,985
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 ...
- 16k
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 ...
- 44.1k
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. ...
- 44.1k
5
votes
Accepted
Is the DNA different in each type of cell? What DNA is passed to offspring?
Most cells in a human body contain a complete set of the genome, which is two sets of 23 chromosomes. Having two of each chromosome is called diploidy.
Within an individual human the DNA is ...
- 16k
5
votes
Accepted
Do babies conceived naturally or artificially have any differences in long-term health?
A review paper on children born by the advent of assisted reproductive technologies (ART) and frozen sperm (Lansac & Royere, 2001) concludes that ART children, as compared to the general ...
- 52.3k
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 ...
- 1,597
4
votes
Symmetry of species
There's really two answers to the question. The first is overall symmetry: mammals, like all tetrapods, are bilaterally symmetric. This comes from a distant common origin with other bilaterally ...
- 492
4
votes
Accepted
Why do fetuses have membranes between fingers and toes?
Short answer
The transient membranes between the fingers and toes in embryos are a myth.
Background
The presence of transient membranes in developing embryos supposedly points to our fishy ...
- 52.3k
4
votes
Accepted
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 ...
- 191
4
votes
Accepted
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 ...
- 35.3k
4
votes
Accepted
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 ...
- 24.7k
4
votes
Accepted
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 ...
- 44.1k
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