Changes in the heritable attributes of populations of organisms over time. The mechanisms of evolution are mutation, migration, drift, and selection.

learn more… | top users | synonyms

3
votes
2answers
96 views

How to name a case of convergent evolution where the same mutation is involved in both lineages?

Definition of Convergent evolution - from Wikipedia > Convergent Evolution Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent ...
2
votes
1answer
54 views

How do I measure genetic distance?

I'm not sure how to measure genetic distance. There seems to be many different equations out there, and all the ones I found are rather old. In my specific problem I want to see if the twist in ...
3
votes
1answer
67 views

Development and function of spindle neurons

In his book How to Create a Mind author Ray Kurzweil makes some claims about spindle neurons that he provides no source for. Concretely he states that spindle cells: Are Involved in handling ...
0
votes
0answers
87 views

Is natural selection still at work in humans in the 21st century? [duplicate]

There has been some disussion on this site about some aspects (e.g. evolution of eye sight, or height, or the effect of medicine, or evolution the past $\sim10000$ years). My question is really more ...
5
votes
3answers
237 views

What is the difference between Founder effect and Bottleneck effect?

Both are examples of genetic drift in which there is a change in the allele frequency when the population size becomes small. What is the difference between the two?
30
votes
4answers
8k views

If evolution is not about increased complexity, why does so much complexity evolve?

In my last question I asked why we don't see increased complexity in artificial life simulations of evolution. It seems I had fallen for a common misconception, that evolution was about improvement by ...
29
votes
3answers
3k views

Why Is Most Life Symmetrical Externally But Not Internally?

Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance. Take a human for instance, make a line from the top of our head right down the middle. However, ...
22
votes
4answers
7k views

Why are not all species hermaphrodites?

If a hermaphrodite animal (like slug, snail, etc) finds a partner they can mate immediately. If another animal with "normal" reproduction (lets say a mouse) finds a partner they can only mate if they ...
12
votes
2answers
320 views

Did Darwin ever reach the conclusion that selection will remove variation?

According to simple models of selection the genetic variance in a population should be reduced by selection. (Fisher's fundamental theorem states that the rate at which a population can evolve is ...
3
votes
0answers
54 views

Diffusion approximation to genetic drift

I am reading from the classical textbook Principles of Population Genetics, Hartl and Clark (pdf here). Introduction Let $f(p,x,t)$ denote the distribution of allele frequency $x$ at time $t$ ...
1
vote
0answers
33 views

Why were the earliest humans hunter gatherers instead of fruit eaters living on trees?

How is it that the earliest humans who evolved from primates (who live on trees and mostly eat fruit) became hunter-gatherers (which seems like a harder, more stressful and more dangerous way to find ...
9
votes
2answers
352 views

Why do women live longer than men?

According to Wikipedia and many other sources, women live substancially longer than men (over 5 years in the U.S.). Men can reproduce for much longer than women. So longer living men would have the ...
7
votes
3answers
392 views

Why are the fertility rates of large predators kept low?

Predators at the top of a food chain, like lions, seem to have a relatively low fertility rate, which fits well to the ecosystem and avoids overpredation. But what is the mechanism that keeps the ...
6
votes
2answers
14k views

Why is dimethyltryptamine (DMT) being released during death?

I'm not very well informed about all the things related to biology and the current achievements of science in this field so if I'm wrong in anything I say, please let me know. Many times I've come ...
3
votes
1answer
229 views

Fecundity per woman in early humans

The average fecundity per woman varies a lot from country to country. I call average fecundity per woman the average number of born children per woman. In Homo sapiens, what was the average fecundity ...
7
votes
2answers
689 views

Why are there so many medicinal plants?

Question Quite a few plant species can be used for medicinal purposes wiki. As an example, Filipendula ulmaria is rich in acetylsalicylic acid (aspirin). An allele that produces a substance which is ...
1
vote
0answers
28 views

What are the evolutionary benefits for herbs having beneficial health effects on humans? [duplicate]

There are many types of plants which produce chemicals which can be beneficial in treating human illnesses, or at least alleviate painful symptoms. Why would they do that? Is it just random chance, ...
14
votes
1answer
2k views

Evolutionarily, why do male rats and horses lack nipples?

Developmentally male rats don't have nipples because (reddit) Testosterone release in the fetal male rat happens before the stage of mammogenesis where the teat is formed whereas other species ...
2
votes
2answers
2k views

Cell evolution: immortality vs reproduction

Many sci fi movies produce interesting ideas and technologies that we seem to be able to realize in real life at some point. "Lucy" was not one of those movies. But Morgan Freeman's speech in the ...
13
votes
1answer
3k views

Do babies resemble their father?

An often heard theory is that newborns and babies resemble the father more than the mother, a theory apparently ignited by a Nature paper by Christenfeld and Hill (1995). Figure 1 shows one of the ...
0
votes
1answer
130 views

How does discontinuous distribution provide evidence for evolution?

One of the evidences for evolution is bio-geographical evidence. In it,'discontinuous distribution' is mostly cited as an evidence. For example, Alligators are found only in south-eastern US & ...
4
votes
1answer
84 views

Are there examples of selection on males influencing female phenotypes?

I've been studying selection on female body color in a sexually dimorphic species and am intrigued by the possibility that selection on males, whether it be through sexual or natural selection, may ...
3
votes
2answers
243 views

What does 'direction' mean in the statement “mutations are non-directional”?

I was reading the Mutation theory of De Vries; there I encountered this following statement: Mutations are discontinuous, random & non-directional.This is in contrast to Darwinism where ...
7
votes
1answer
629 views

Why are eggs “egg” shaped?

Is there a reason as to why chickens lay "egg" shaped eggs, as opposed to spherically shaped eggs (or a random shape)? <--- Main Question For extra points (actually just to add more words in ...
9
votes
2answers
906 views

What is the evolutionary explanation for bat's echolocation [closed]

The bat's ability for echolocation is amazing (so are other the abilities of other animals). I was wondering how all of it came to be.
1
vote
0answers
54 views

Why are there different species of bacteria?

The usual (high school or intro to bio) explanation for diversification of species comes from multicellular, usually sexually reproducing organisms, and seems to be closely tied to the biological ...
3
votes
0answers
61 views

How did dolpins acquire the dorsal fin?

I had been thinking bout atavism when I saw a picture of a dolphin. I had seen it before, but suddenly the dorsal fin startled me. How did this dorsal fin evolve, especially, is it some atavism from ...
1
vote
1answer
99 views

What's the mechanism or structure responsible for new species genetic code generation? [closed]

I always had this question in mind. I think, If humans find answer to it then we can trigger the next evolution of human specie. What is the mechanism or structure responsible for evolution ? I don't ...
-2
votes
1answer
82 views

Why plants and animals are so different even though they come from the same ancestors?

All the documentaries I have watched, books I have read so far on the starting of life on earth only talk about animals. The very first life form on earth was bacteria. Then evolution took us this far....
1
vote
2answers
115 views

Are human beings evolved to eat meat? [duplicate]

I know humans can cook, and prepare almost anything, but are humans specifically adapted to eat meat. One of my doubts humans are not particularly well adapted to eat meat because they lack canine ...
4
votes
0answers
93 views

Escaping resource limitations during tumor evolution

In their discussion of the importance of r- and K-selection on tumors, Aktipis et al. (2013; figure 3) provide the following illustration of a hypothetical cancer growth curve: In it, you can see ...
0
votes
0answers
111 views

Why did multicellular organisms evolve when a single cell can survive on its own? [duplicate]

Since unicellular organisms can survive, why would there be evolution of multicellular organisms?
3
votes
2answers
94 views

Crossing over and exon shuffling?

Campbell Biology 10e, in discussing the functions of introns, writes: The presence of introns in a gene may facilitate the evolution of new and potentially beneficial proteins as a result of a ...
1
vote
1answer
55 views

Why did eukaryotic cells develop? [closed]

If eukaryotic cells can survive in extreme conditions, then why are their still prokaryotic organisms?
3
votes
0answers
59 views

Do animals demonstrate target practice (i.e., playful accuracy behavior)?

Do animals demonstrate any sort of accuracy-motivated play? (please provide examples!) Consider most human sports and related hobbies. Most share the common goal of hitting a target or being accurate,...
24
votes
5answers
2k views

Why are there species instead of a continuum of various animals?

As I understand it, various animal traits have to evolve gradually, but what happens to the species that are "neither here nor there"? To put it differently, if a species evolved from another, it did ...
5
votes
1answer
81 views

Evolution of dominance of alleles

Can someone tell me where can I find detailed text about mechanisms of evolution of dominance? Or, if it is possible, I would be grateful if someone will tell me about them here.
5
votes
1answer
159 views

The replicator equation vs the Lotka-Volterra equation

Background The replicator equation with $n$ strategies is given by the differential equation: \begin{equation} \dot x_{i} = x_{i} \left( \sum_{j=1}^{n} a_{ij}x_{j} - \phi \right) \qquad i = 1, \...
3
votes
0answers
49 views

Does the bending of a tree's trunk in the wind stimulate and strengthen root growth?

Recently Southern California experienced extreme wind velocities and afterwards the news reported over 300 trees had fallen in San Diego County. I had either heard or read somewhere that the action of ...
3
votes
1answer
104 views

What came first? The DNA or the DNA polymerases?

I know this sounds a lot like chicken and egg question and while the latter has an answer, I am intrigued about the former. A modified form of the question would be, in the course of abiogenesis, ...
2
votes
1answer
706 views

Examples of animals with 12-28 legs?

Many commonly known animals' limbs usually number between 0 and 10. For example, a non-exhaustive list: snakes have 0 Members of Bipedidae have 2 legs. Birds and humans have 2 legs (but 4 limbs) ...
0
votes
1answer
53 views

Is it known how human sweat glands evolved?

If human descends from apes than probably we lost our hair. Perhaps in the age of homo erectus we lost our hairs and began transpiring through our skin with sweat glands. But how did these glands ...
2
votes
3answers
8k views

Why do our eyes close when we sleep?

Why do our eyes close when we sleep? Is it to relax our eye muscles? How can it be explained from an evolutionary point of view?
1
vote
1answer
88 views

Evidence of species transitions [closed]

I had a debate with a person who believes in some kind of creativism, let's call it that way. And in the middle of the "debate", an interesting question popped up. What are evidences of "...
1
vote
0answers
43 views

Was the frequency of mutations more during primitive earth due to radioactivity?

Primitive earth was more radioactive (or was it really?) according to radiometric analysis of C14 which suddenly appeared at 4250 million years in the Hadeon eon. Is it possible that ancient high ...
7
votes
1answer
73 views

Why does the proportion of transposable elements vary so much across species?

Intuitively, transposable elements (TEs) are harmful as they may cause genome instability. However, some people argue that TEs are also sources of variations, especially regulatory sequences[1]. If ...
2
votes
0answers
27 views

The evolution of sleep [duplicate]

Are there evolutionary theories as to why we (and most animals) sleep? Some claimed functions of sleep include: restoration, waste clearance, memory processing, etc. But unless we understand why ...
3
votes
0answers
75 views

Why doesn't lard taste good? [closed]

I mean looking from evolutionary perspective sugar tastes sweet and individuals that had this perception ate more sugar and survived and those that didn't perceive sugar as sweet didn't eat it and ...
11
votes
3answers
3k views

Why did abiogenesis only happen once?

If the "primordial soup" theory of abiogenesis is to be believed, self-reproducing organisms spontaneously arose on Earth at least 3.5 billion years ago, surprisingly soon after the Earth cooled down ...
10
votes
2answers
7k views

Why are the Galápagos islands so special?

Why did Darwin formulate his theory of evolution just after his visit to the Galápagos islands? Why were they so special from an evolutionary point of view?