Changes in the heritable attributes of populations of organisms over time. Major mechanisms include drift, natural selection, mutation, and gene flow (migration).

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Can species back-evolve?

One of the tenets of Darwin's theory is the survival of the fittest, ie adaptation of features that allow a species to adapt better to its surrounding environment. I am wondering that given the right ...
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When has an organism evolved enough to be called a new species?

Imagine that we take a population of horses, split them in half and place them in completely different environments. The two species will evolve separate from each other and because the environment is ...
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Is it known how the first viruses formed?

The oldest known virus is known to have infected prehistoric insects 300 million years ago. A virus is basically a parasitic strand if DNA or RNA encapsulated in a protein coat. It enters cells by ...
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417 views

Evolution in 37 years, is it possible?

I am confused, can evolution ( speciation ) really occur in such a short time ? In 1971, biologists moved five adult pairs of Italian wall lizards from their home island of Pod Kopiste, in the ...
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Do men have more extreme variations than women?

This question was considered unsuitable for Skeptics and I think it is more suited to BIology than Cognitive Sciences I was reading this article which I found interesting. It is not supported with ...
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450 views

The Origin of Mitochondria

For a long time I've just accepted, because it is just what everyone told me, that mitochondria became organelles in the cell when they were "engulfed" by another cell which acted like it's host. This ...
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328 views

How do members of cryptic species know who to mate with?

According to Wikipedia: In biology, a cryptic species complex is a group of species which satisfy the biological definition of species—that is, they are reproductively isolated from each ...
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Is there a biological mechanism for evolution encoded into our DNA?

Throughout high school, I remember learning about Darwin's theory of evolution as if it were near-fact. But something always seemed wrong about the ideas presented. Survival of the fittest Random ...
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373 views

Is it the case that all changes in phenotype during life are not inheritable?

This came up in a talk with a friend. I wanted to clear this doubt. I've read about it before and did again after her remark (my thoughts didn't change: her concept is Lamarck's, not Darwin's), but ...
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Is Behe's experiment (evolving the bacterial flagellum) plausible in the lab?

[Warning: this question is motivated by a prominent proponent of "intelligent design": Prof. Michael Behe. I'm not interested in debating creationism.] According to Wikipedia[1]: In Darwin’s ...
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575 views

Book recommendation on population/evolutionary genetics?

I have recently been involved in collaborations that require me to model the population genetics of eukaryotic populations. I fear I may either be "re-inventing the wheel" or making conceptual ...
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243 views

How do we know that dinosaurs were related to lizards and/or birds?

Do we clearly know what the living closest relative of the dinosaurs are? And connected to the first question, in scientific manner how do we know these relationship between extinct species and living ...
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521 views

When did vision evolve for the first time?

Today I wondered what the first organism to evolve vision would have been. I assume that it would have been kind of primitive and basic, but of course extremely innovative and eventually useful to a ...
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217 views

Abiogenesis: Beyond the research journals as a lead in to discussions on evolution

I just came across this abstract: Aminoacyl-tRNA synthetases (aaRSs) are responsible for creating the pool of correctly charged aminoacyl-tRNAs that are necessary for the translation of genetic ...
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552 views

Did researchers evolve multicellular yeast or did they just turn on multicellularity?

In this new paper "Experimental evolution of multicellularity" found via Ars Technica the researchers describe having developed multicellularity and apoptosis within 60 days from a unicellular yeast ...
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261 views

Evolution of long necks in giraffes

In this question, the OP uses giraffe necks as a supportive example of evolution. Is the mechanism described in this post accurate? At some point, I thought I remember hearing that giraffes did not ...
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372 views

Is there any reason for the variation in mitochondrial DNA size?

As my textbook An Introduction to Genetic Analysis points out, yeast mitochondrial DNA has approximately 78 kb of genetic data, while the human mitochondrial DNA contains 17 kb. Is there any evolution ...
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How did the huge dinosaurs cope with gravity and loads on bones, etc.?

It's very costly to be a huge animal. Your mass grows in cube when you scale up, but you still only have two/four legs to support the same weight. This increases the pressure that your body needs to ...
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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?
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What was the reason for some plant and animals to become giant in course of evolution?

The dinosaurs, mammoths, giant plants etc are known to be bigger than modern animals. I wonder why they had been lived and why they are not living now? I really don't know much but is it something ...
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Why do parasites sometimes kill their hosts?

It's bothered me for a while now. I understand why a parasitoid would do this, as it only temporarily requires the host, and that not all parasites kill their hosts. There seems to be no evolutionary ...
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206 views

Are there any pre-Holocene venomous animals?

The novel (and subsequently movie) Jurassic Park featured a dinosaur called Dilophosaurus, that was purported to be venomous and had an ability similar to that of the extant spitting cobra. ...
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497 views

How did the human brain evolve?

A common question posed is, "how did the eye evolve?", because the eye is so complex. However, this has been answered rather clearly and there are several examples around the world of animals in ...
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371 views

What are the evolutionary niches differentiating an apple from a pear?

So, as far as I understand (basic) evolutionary theories, diversity is generated by "niching." That is, if there is an environmental factor that hasn't been fully used by any species to "profit" off, ...
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368 views

Why do pandas have a high probability of giving birth to twins?

According to the BBC documentary "Wild About Pandas", about half of panda birth result in twins. Why do they have such a high probability compared to other mammals? What factor(s) control that ...
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248 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 ...
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825 views

Is there an evolutionary advantage to crying when sad?

It seems as though the act of crying when sad does nothing to relieve that sadness. Is there an advantage to crying from an evolutionary perspective, or is it the end result of a different process? ...
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129 views

Beginning of the urogenital system

Are any invertebrate nephridia (proto/meta) homologous with vertebrate kidneys in the sense that embryologically they also begin together with the genital system? When did the embryologic association ...
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Why, specifically, does each generation, on average, improve upon the design of the species rather than degrade it?

In every non-life example I can envision, a copy of a copy is always a degraded or less pure version of the original unless some outside influence acts to correct the copy back toward the ideal ...
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723 views

The evolutionary process in bird wings, especially with regard to winglets

In this answer on aviation.SE a comparison is made between the shapes of airplanes wings and the shapes of birds wings. It concludes with the following remark: After all, no bird has winglets. Not ...
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How did the first self replicating organism come into existence?

When people try to explain evolution, they tell me that evolution is a cumulative result of mutations & natural section of the more superior individuals of a particular species. I think I'm fairly ...
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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 ...
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180 views

Is there an “evolutionary species similarity calculator”?

Is there a website where I can input pairs of species and get an "evolutionary similarity score"? E.g. (numbers are completely made up) Input: Chimp and Human, Output: 97% Input: Cat and Human, ...
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209 views

Did we first have swimming birds or flying birds?

Looking at the swimming birds building nests just across my garden, I suddenly wondered how evolution came to swimming birds and whether flying birds started swimming or whether swimming bird like ...
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Have we ever observed two drosophila lineages that evolved reproductive isolation in labs?

Background The standard definition of species refers to the concept of reproductive isolation. If two lineages are found to be reproductively isolated, then we consider these two lineages to belong ...
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Is there any evolutionary advantage of selection of L-amino acid over D-amino acid?

After listening to a scientific talk, I had this question that why in the natural selection process, are the L-amino acids selected over the D- form. However, we still we produce D-amino acids; ...
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445 views

How does the genetic code evolve?

After looking at this question, some other questions poped in my mind. The DNA code is redundant, there are 20 amino acids for 64 possible nucleotide combinations. Therefore some amino acid are coded ...
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Formation of Life

Originally, life evolved from non-living matter. Why is life only generated from other life nowadays, and why doesn't it evolve from inanimate matter, like it did originally billions of years ago, ...
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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 ...
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Is there any evidence that a virus can modify human evolution

I was just reading Evolution of lactose tolerance, and in it one line says "But there was a time in human history when our diet and environment conspired to create conditions that mimicked those of a ...
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What is the Edward O. Wilson fuss about?

I have just read this article on E. O. Wilson and I don't understand what the difference is between what he is arguing and "standard" natural selection. I read "the extended phenotype" some years ago ...
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What advantage would the initial 'donor' in horizontal gene transfer by conjugation have received?

I am struggling to think why horizontal gene transfer between bacteria would have persisted during the course of evolution as surely it puts the 'donor' at a disadvantage? For example, consider a ...
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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 ...
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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 ...
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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 ...
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Why does the butterfly have a cocoon stage in its life cycle?

Why does the butterfly have a cocoon stage in its life cycle? It could have simply grown up within the egg/cocoon, and emerged as a butterfly. Instead it is first an egg, then a worm, then a ...
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What is the closest species to humans in animal kingdom?

I presumed chimpanzees were the closest relatives of us. However, after watching this TED Talk, it seems bonobos are closer to us both in skeleton and behavioral similarity than chimpanzees. I once ...
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155 views

Why is green fur not a thing?

In most biomes on earth, and certainly in the most densely-populated, the best camouflage color or pattern for an animal would be a variant of green, so as to blend in with the leaves and grasses of ...
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837 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.
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What is the modern state of the theory of evolution?

When I studied biology at my medical school we used to learn things about a century old: the famous Darwin's voyage on "Beagle" to the Galapagos Islands, the classical triad of his Theory of ...