Evolution refers to the observed changes in successive generations of biological organisms due to heritable components (genes and DNA). Charles Darwin proposed a major mechanism of evolution: natural selection.
8
votes
3answers
915 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 ...
3
votes
1answer
103 views
Is a “Fact” any theory for which there is overwhelming evidence in any field other than biology?
Evolution is often described as a fact, and a theory. Evolution is a heavily overloaded term, with one definition being the fact that, "changes in the frequency of alleles in populations of organisms ...
9
votes
1answer
131 views
In which order did the cells of the immune system evolve?
Thinking about how complex the interactions between different types of immune system cells (T-helpers, T-Killers, Phagocytes, B-Cells etc.) are, it's fascinating how they all combine to get the ...
5
votes
1answer
112 views
Is local equilibrium a reasonable assumption for evolutionary processes?
Whenever I look at discussions of fitness landscapes (in particular, Kauffman's NK model) the questions tend to resemble:
The population is at a local equilibrium, but another equilibrium of ...
1
vote
3answers
160 views
How did this spider evolve to mimic exactly a human face and arms?
So I came across something terribly amazing today, that is, a video showing this species of peacock-spider, that literally, transforms into a human face waving his arms about.
What could have ...
3
votes
1answer
63 views
When does weak selection produce qualitatively different results from strong selection?
In evolutionary game theory, it is typical to model organisms as having a base fitness that is modified slightly by the game interaction. The ratio of the game effect versus the base fitness ...
3
votes
1answer
77 views
Are there natural selection experiments that quantitatively agree with theoretical modeling?
Has anyone ever conducted an evolution experiment and quantitatively compared it to theory? For example, has anyone ever put bacteria in a million petri dishes filled with antibiotics and calculated ...
1
vote
2answers
43 views
Which texts are good for beginners to understand evolution on the genetic scope?
Are there good texts to study the evolution, how it works, and how mutations and changes lead to evolution of the organism ?
And how does the information increase through the long time using ...
31
votes
2answers
586 views
Is there any evidence that sexual selection may lead to extinction of species?
Darwin suggested that sexual selection, especially by female choice, may counter natural selection. Theoretical models, such as a Fisherian runaway process, suggest that evolution of preference and ...
0
votes
1answer
42 views
What are the differences between G+ and G- bacteria?
The distinction between Gram-positive and Gram-negative bacteria is based upon the Gram staining method, that reflects the bacterial wall physical properties.
However, this classification involves ...
7
votes
1answer
101 views
What is the evolutionary reason behind the fragility of teeth?
Almost all organs in the human body have a rather large threshold within which the organ or tissue is capable of repairing itself using materials supplied by the body, whether it's made from organic ...
0
votes
3answers
57 views
What are the allowed evolution operators (on protein encoding sequences)?
What are the evolution operators, meaning allowed actions on the DNA sequence that encodes a protein.
I assume all evolution of genes is a result of duplication errors. So an answer could look ...
2
votes
1answer
63 views
Why do humans bury their dead?
As far as we know Ape Men or the Neanderthal Man was the first to bury its dead. My question is why.
I don't think they practiced religion or believed in spirits or faith or stuff like that. ...
6
votes
1answer
79 views
Same 185th million grandfather?
I was watching a lecture by Richard Dawkins earlier today and he mentioned that “Your 185th million grandfather was a fish.” I started wondering about the following question,
Is it true that my 185th ...
-4
votes
0answers
29 views
Less Evolved Humans? [closed]
In Homo Sapiens we see that evolution caused the dense hair growth to be altered to a more fine growth of hair on the body( at parts like hands and feet)..
Therefore can we assume that people having ...
2
votes
2answers
53 views
Evolution after the development of sexual reproduction
My understanding of evolution is that genetic mutation occurs in individual members of a species, and they become a new species.
Isn't a definition of species a group of genetically similar organisms ...
4
votes
1answer
43 views
What determined the evolution of different faces in humans?
The most distinctive characteristic of a human is it's face - it is unique among each individual (with the exception of identical twins). It is uncertain to me if whether we best identify other humans ...
7
votes
2answers
138 views
Does pheomelanin have a useful biological function?
Melanin is a natural pigment that is categorized into two main forms, eumelanin and pheomelanin. It's well documented in the science literature that increased eumelanin levels reduces the risk of ...
-2
votes
1answer
72 views
Are we evolving to age slower, or to live longer aging at the same rate?
I wonder why most of us find senior people lovely and charming. Is it because to love grandpa and granny is vital to our survival as a species, in the same way as we love babies? If so, it would mean ...
5
votes
2answers
80 views
Can any species be bred selectively/engineered to become as diverse looking as dogs?
I've done some research and it appears that dogs are the most diverse looking single species of mammals. The questions that interest me is - are dogs special in respect to genes/gene activation ...
2
votes
1answer
38 views
Would non-human carnivores be able to survive on farmed foods?
Certain creatures that are considered carnivores are non-obligate carnivores and are technically omnivores (such as wolves/dogs). How different is the potential digestive ability of these species ...
6
votes
3answers
287 views
If Evolution Is In Progress, Why Fight Extinction?
Natural selection is a central tenet of evolution. However, most biologists seem determined to prevent the extinction of the species that have been selected against. Why is this? Preservation of ...
8
votes
4answers
332 views
What is meant in biology by the term “evolved”?
A student asked me this the other day and I thought that I would ask it again here. If one organism is said to be "more evolved" than another, what exactly does this mean?
1
vote
3answers
2k views
Evolutionally speaking, why do humans have 46 chromosomes
In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Monkeys, chimpanzees, and Apes have 24 pairs (twenty-four pairs), for a total of 48.
What caused humans to have 46?
...
1
vote
1answer
124 views
Evolutionary speaking, what is the purpose of girls masturbating?
In males they expel sperm in semen, but females orgasm with clitoral stimulation, and the clitoris has absolutely no evolutionary, sexually reproductive, or otherwise purpose outside of sexual ...
4
votes
1answer
81 views
Experimental evidence for the selfish gene vs. the selfish individual
In the Selfish Gene, Dawkins makes the argument that a better view of evolution (i.e. more in accordance with experiment) is obtained if you view the basic unit of evolution to be the gene rather ...
0
votes
0answers
21 views
What are the superiorities and inferiorities between livestock animals (cow, sheep, goat, etc)?
I'm trying to understand the effect of human race on the evolution of livestock animals (i.e.; how we end up producing currently known ones).
It is obvious that, even today, farmers don't produce ...
10
votes
2answers
247 views
Is there any recent evidence for the aquatic ape theory of human evolution?
aquatic ape theory suggests that many features that distinguish humans from their nearest evolutionary relatives emerged because the ancestors of humans underwent a period when they were adapting to ...
1
vote
3answers
106 views
Has medical progress stopped human evolution?
We can cure many diseases nowadays, and thus the natural selection is very limited.
Plus, mankind spent the whole beginning of its existence in almost the same hostile environment, and that's where he ...
2
votes
2answers
98 views
Why is a slow worm not considered a snake?
Slow worms are considered lizards as opposed to snakes, both are reptiles. Now I get that there are traits that distinguish them (eye lids, ears ...). But snake species themselves vary already quite a ...
2
votes
2answers
31 views
How did the activities of protocells become inheritable?
I have learned that first a protocell came to exist and its characteristics came to be passed on by genetic material. So how come genes for all the activities come to incorporate into genetic ...
22
votes
3answers
2k views
Why do eukaryotic organisms have introns in their DNA?
We touched on introns and exons in my bio class, but unfortunately we didn't really talk about why Eukaryotes have introns. It would seem they would have to have some purpose since prokaryotes do not ...
3
votes
1answer
48 views
What are some examples of scaling laws in biology?
I've seen that metabolic rate scales logarithmically as function of mass for many animals over an extremely large span of parameters. What other scaling laws exist at the individual level?
15
votes
4answers
757 views
Why are there exactly four nucleobases in DNA?
Does someone know why DNA is composed of four nucleobases? In particular, is there an explanation for the number? Why four and not two, or eight?
14
votes
3answers
793 views
Why are there no wheeled animals?
In physics, "almost everything is already discovered, and all that remains is to fill a few unimportant holes." (See Jolly.) Therefore, on Physics SE, people are veering off into different directions: ...
17
votes
3answers
424 views
How many times did endosymbiosis occur?
According to the endosymbiont theory, mitochondria and chloroplasts originated as bacteria which were engulfed by larger cells. How many times is it estimated that this occurred in the past? Are there ...
9
votes
3answers
4k views
What is the difference between orthologs, paralogs and homologs?
These three terms are often misused in the literature. Many researchers seem to use them as synonymous. So, what is the definition of each of these terms and how do they differ from one another?
3
votes
1answer
83 views
Why do sloths come down from the trees to defecate?
I'm under the impression that most sloths exhibit this behavior, but why? They are slow moving and so have no way of escaping from predators when on the ground. Not to mention the energy they expire ...
2
votes
1answer
78 views
The oldest common ancesstor of all human beings
Do all human beings have a single oldest ancestor (a man and a woman), or were there were many ancestors at the same time at different places on earth?
This article sheds some light. Is there another ...
13
votes
4answers
687 views
Can two humans with 44 chromosomes produce viable offspring?
It is known that there are very few individuals having 44 chromosomes, not the usual 46 chromosomes.
One example is a male in China: the first article, the second article.
The other is a female in ...
4
votes
1answer
202 views
Why does sexual selection evolve beautiful features?
First question here. I have a very raw understanding of sexual selection:
Say a group of females of a certain species "likes" some feature of a certain groups of males; by "like" I mean some ...
10
votes
1answer
223 views
Is there are evolutionary explanation for why humans and primates are ticklish? How might it have evolved?
Tickling is a rather interesting phenomenon: When humans or apes are touched in certain areas like the armpits or sides, we respond with laughter AND frantic attempts to stop the assault. Obviously ...
11
votes
1answer
426 views
Is there an advantage to linear chromosomes?
The DNA copying enzymes have a hard time working to the end of a chromosome. For circular chromosomes this is not a problem, since there is not a sharp 'end'. However, for a linear chromosome, without ...
2
votes
1answer
75 views
Macroevolution vs. microevolution
Where is the line usually drawn between macroevolution and microevolution?
I thought that, although similar processes govern both, the line was at the species level, with macroevolution being changes ...
0
votes
1answer
61 views
Lineage selection in plasmid evolution
I've been reading through Paulsson (2002) and I am not sure what he means by "lineage selection" in the second to last section. The paper deals with plasmid replication, and mostly concentrates on the ...
7
votes
3answers
159 views
Mathematical Modelling of Natural Selection
I'm a math undergrad looking for some papers on modelling the process of natural selection. The only paper I've been able to find is by the pre-eminent mathematician Herbert Wilf from 2010,
There's ...
4
votes
0answers
49 views
Structure of fitness landscapes in the NK model
The NK model of rugged fitness landscapes consists of $N$ sites where fitness contribution of each site depends on its state $\{0,1\}$ and is epistatically affected by $K$ other sites. When defining ...
11
votes
4answers
531 views
Are there any examples of sudden leaps in evolution?
As far as I understand, various abilities like flying, sight, hearing etc. were caused by slow evolution, where those with a greater ability to to these things had better chance of survival. (If this ...
1
vote
1answer
73 views
Reproductive isolation causing evolution
My course book says about reproductive isolation that it does not allow the interbreeding among the individuals of different species. It also says that it is a cause of evolution.
How is this cause ...
0
votes
1answer
47 views
Why does the PR form of phytochrome exist?
I know how it gets converted because PR is more stable and when there is neither red or far red light PFR naturally converts to PR. But what is the point of it? If PFR is the biologically active one ...
