237
votes
Why are so few foods blue?
Short answer
Blue color is not only rare in edible organisms - Blue color is rare in both the animal and plant Kingdoms in general. In animals, blue coloring is generated through structural optic ...
- 52.3k
133
votes
Accepted
Why is the heart not in the middle of the body?
First of all, let me make it clear that the heart is at the vertical centre of the body -- it is not shifted towards left (or right). However, it is slightly tilted towards the left in most cases.
...
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127
votes
Why are so few foods blue?
Although @AliceD's answer is a great simple demonstration of the rarity of blue in our natural world, there's likely a more nuanced/technical reason.
Short answer
Blue light was the most available ...
- 29.7k
106
votes
Accepted
How could humans have interbred with Neanderthals if we're a different species?
Short answer
The concept of species is poorly defined and is often misleading. The concepts of lineage and clade / monophyletic group are much more helpful. IMO, the only usefulness of this poorly ...
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102
votes
Is evolution a fact?
A tiny bit of terminology
Fact
In popular culture, the term fact means "something that is true". I would consider a theory as being the closest concept in science to what is called a fact in the ...
- 68k
75
votes
Accepted
Are humans the only species who drink milk as adults?
Good observation!
Gene coding for the lactase
Gene LCT
Mammals have a gene (called LCT C/T-13910) coding for the lactase enzyme, a protein able to digest lactose. ...
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74
votes
Accepted
What is the evolutionary advantage of red-green color blindness?
Short answer
Color-blind subjects are better at detecting color-camouflaged objects. This may give color blinds an advantage in terms of spotting hidden dangers (predators) or finding camouflaged ...
- 52.3k
55
votes
Accepted
If evolution is not about increased complexity, why does so much complexity evolve?
I think possibly the problem here is the way you're approaching the issue.
You're considering improvement as anything that increases the abilities or complexity of the organism—that isn't necessarily ...
- 638
55
votes
Accepted
Does it make sense to classify all humans in a single species?
Actually, we not only consider that all human beings belong to the same species (Homo sapiens) but even that we belong to the same subspecies (Homo sapiens sapiens). So, does it really makes sense?
...
- 68k
52
votes
Accepted
Does animal blood, esp. human, really have similar salinity as ocean water, and does that prove anything about evolution?
Short answer
Early sea water had a very different osmolality than blood plasma.
Background
The reference range of serum osmolality is 275–295 mosm/kg (mmol/kg) (MedScape). The osmolarity of sea water ...
- 52.3k
43
votes
Accepted
Why do human females have periods?
Short answer
Shedding or reabsorbing the endometrial lining is energetically advantageous to the female.The advantage of shedding over re-absorption may be that sperm-born pathogens are removed from ...
- 52.3k
42
votes
Are there life forms that freely fly in the atmosphere?
It sounds like you are talking about aeroplankton, a general term for a wide range of tiny life-forms borne on the wind.
While some of these are essentially passive while airborne (e.g., pollen, ...
- 6,977
39
votes
Accepted
Are there animals that have evolved a resistance to human activity or encroachment?
Note: This is an answer to the last line of your question.
A classical example of animals adapting to the influence of humans on their environment is the adaption of the Peppered Moth.
Here is a brief ...
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37
votes
Accepted
How did the cardiovascular system evolve?
While others have addressed the big picture aspects of your question, I think it would be useful to look at the specifics.
Have a look at the heart (or more accurately, the hearts) of the earthworm: ...
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37
votes
What is the function of epidermal ridges on human fingers (that produce fingerprints)?
I found many plausible claims that fingerprints increase friction. However, the following article claims, at least under their experimental conditions, that fingerprints actually decrease friction ...
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37
votes
Accepted
Are mutations a source of genetic variation?
Going through the possible answers
(A) Rates tend to be very high in most populations.
This is a very unclear statement. What does "high" mean? In humans, the average mutation rate per ...
- 68k
36
votes
Is evolution a fact?
A scientific fact is something that is true. A fact cannot be proven false. This is no different from the common usage of the word. However, in science, we often do not definitively know what is true. ...
- 2,472
35
votes
Are humans the only species who drink milk as adults?
The problem with this question is 1) wording and 2) access.
"Drink" and "digest thoroughly" are two different things. The latter does not prohibit the former. It is only lactose that is not tolerated;...
- 24.7k
35
votes
Accepted
Did predators evolve eyes first?
Short answer
Complex eyes may have evolved first in predator species, specifically in box jellyfish. Trilobites are another group of animals where complex eyes may have evolved first. The trilobites ...
- 52.3k
34
votes
Accepted
How do we know that our genetic similarities to other species is actually due to common ancestry?
We don't know, and we never will. Science doesn't work that way. But evolution is the simplest hypothesis that is both falsifiable and consistent with lots of experimental data. Therefore it is the ...
- 5,675
34
votes
What is the function of epidermal ridges on human fingers (that produce fingerprints)?
To balance the debate, from a neutralist evolutionary perspective...
There does NOT have to be a direct selective pressure for a trait's contribution to an organism's expressed phenotype.
Three ...
- 3,577
33
votes
Why haven't prey evolved the ability to always outrun their predators?
There are (at least) three important factors to consider here; evolution under selection requires genetic variation upon which to act, selection can act on covarying traits causing trade-offs, and ...
- 16k
31
votes
Accepted
Why do living fossils like crocodiles remain so constant and not evolve?
Evolution is a process of change by four mechanisms; mutation, migration, drift, and selection.
You are correct in thinking that, because crocodiles have been around for a long time, they could have ...
- 16k
30
votes
How did the felines get to America?
Short answer
It is believed that low water levels occurring several times during the last ten million years facilitated migration and divergent evolution of the felids. The North-American ocelot, lynx,...
- 52.3k
29
votes
Does animal blood, esp. human, really have similar salinity as ocean water, and does that prove anything about evolution?
The argument that blood plasma resembles sea-water, in essence, relies on the notable similarity in concentration of two ions in plasma and sea-water, compared with their intracellular concentration: ...
- 4,678
28
votes
Accepted
Why do men have nipples?
The two key concepts here are:
sex-specific selection, and the fact that
males and females share the majority of genes
1) sex-specific selection
Obviously, any population where females lacked ...
27
votes
Is evolution a fact?
Tl/dr: No, evolution is not a fact (unless your definition of fact defines evolution to be a fact, in which case it is a fact...). And if that phrase ruffles your feathers, it suggests you should ...
- 1,364
27
votes
Accepted
How can birds disperse seeds when they are able to digest them?
Birds may indeed digest seeds under conditions of rest. It has been postulated that almost all current knowledge on mechanisms of internal seed dispersal has been obtained from experiments with ...
- 52.3k
25
votes
Accepted
Is there a bacterium that became a virus?
This virology site has a post about a 2017 paper about membrane-vesicled plasmids that act in ways that are theorized to be precursors to how viruses work:
It is likely that the plasmid-containing ...
- 5,568
Only top scored, non community-wiki answers of a minimum length are eligible