Questions tagged [evolution]

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

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54 views

How symmetrical can an organism be?

The majority of living things have some form of symmetry. Many mammals and fish have bi-symmetry, and anemones, starfish and jellyfish (among others) have radial symmetry. However, there usually are ...
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what chromatin factors are the most potent supressors of meiotic crossover?

I think linker histone H1 is probably involved, but the literature is scant. What else prevents crossovers from becoming hyper-frequent during meiosis?
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Why don't all organisms reproduce asexually?

According to a comment at Why are not all species hermaphrodites?, asexually reproducing species go extinct more easily. However, I don't think sexual reproduction is a true evolutionary stable ...
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Do squids or octopus suffer from myopia(hyperopia)? Do other vertebrates get myopia(hyperopia)?

Both vertebrates and cephalopods evolved very sophisticated camera-type eyes, and both are capable of focus. But it also pose a risk of inability of focusing, such as myopia in human. So is myopia a ...
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What is the evolutionary significance of germ cell migration to gonads?

Why do germ cells have a different origin than the gonadal organs? Does it help the animals in any way? P.S. I know it is difficult to answer whys in biology but is there any theory as why do they ...
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What theories exist as to how self-replicating molecules organised into the first cells?

When I was a biology student in the early 90's, what I learned and read seemed to indicate a gap in theories around the origins of life. There was, of course, no real evidence about how the first self-...
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176 views

To what extent do fossils change over time?

Fossils are formed over millions of years. How do scientists quantify the extent to which a particular fossil has changed in shape/relative tissue density/etc. over geological timescales (if at all)? ...
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The first species having circle of Willis (circulus arteriosus cerebri)?

I know mammals are not the only species that have this anatomical unit (i.e. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982101/). But I was wondering what was the first species that had a similar ...
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131 views

Why are brightly coloured marine animals thought not to display aposematism?

There are many brightly coloured marine animals, such as fish, corals, sea stars, and octopodes. And yet Wikipaedia says it is thought that those colours don't serve to deter predators, while they do ...
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330 views

How did we get self-aware?

Imagine being under a lot of stone age people and you are the only one who thinks something like "Hey I am a human being, and now I am thinking about this and that and maybe I change myself to become ...
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109 views

Why does female's age of puberty inform on mating system?

Reading from Does increased calorie intake cause increase in libido in humans?, @AlexStone says: I'm aware that humans have a dual mating strategy - somewhere between pair bond and casual mating. ...
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772 views

Why do horses recycle their endometrial lining while humans don't?

How does not recycling the endometrial lining of the uterus benefit humans (and other organisms that menstruate), while recycling it is beneficial to horses (and other organisms that undergo estrus ...
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60 views

Ecological specialization and relative abundance

I am reading Evolution in Changing Environments by R. Levin but have a hard time. Claim At page 25, Levin says as a conclusion The more efficient a caste at meeting the contingency for which it ...
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142 views

What were the Neanderthal innovations?

At some point the neanderthal and modern human lineages diverged. I'm not sure what exactly their most common recent ancestor was (I see some sources suggesting homo heidelbergensis), but in any case ...
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77 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 ...
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191 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 ...
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54 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 ...
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Resources for similarity between embryos

Is there a scientific paper/reputable image resource out there which I can use that the embryos of different organisms (vertebrata) are similar in their early developmental stages(without falling into ...
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639 views

How can the number of chromosome change during evolution

I found an explanation here, which is basically saying that sometimes the centromeres are duplicated, breaking a chromosome into two halves. But how could this propagate? I don't think inbreeding is ...
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Seeing through the rain

This question leads me to wonder about seeing in and through rain. From visual point of view, rain is light-bending droplets moving downwards, unformly in steady rain, less uniformly if there's ...
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Evolution of a Population

Scientists observe a newly established population of sexually reproducing plants growing on the shore of a small island. An observable trait of the plant has two possible phenotypes. It is determined ...
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How octopus develops its imitation skill?

I've watched one documentary about a Mimic octopus which they can imitate another animals in several form e.g. a Lion fish, a Sea snake, a Flatfish, etc. My question is how these octopuses can have ...
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377 views

How did the double circulatory system evolve from the single circulatory system

I already learned how the mammal circulatory system (double circulatory system) evolved from the reptilian circulatory system. How did natural selection evolve the reptilian circulatory system and the ...
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Name/Examples of Traits whose benefit is non-obvious and/or which evolve despite apparent mal-adaptivness?

I'm a graduate student in cognitive science doing work on people's explanations and learning, particularly having to do with natural selection. Often, students misunderstand natural selection as a "...
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Are amantadine and rimantadine MOAs unknown to evolution?

Are any natural (human or otherwise) antiviral mechanisms similar to the antiviral mechanisms of amantadine and rimantadine, or are these mechanisms undiscovered by evolution? Are drug researchers ...
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863 views

Were we able to create vitamin B12 in past?

All herbivores produce vitamin B12 de novo. Gorillas, for example, are "vegans" so I suppose some human ancestor was also herbivore. Have we ever been B12 self-producers? If so, why have we lost that ...
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First documented beneficial mutation?

I've been reading up on beneficial mutations, and am curious when we discovered and documented the first one. Can anyone point me to the first documented beneficial mutation? Per request, let me try ...
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278 views

Do Parasaurolophus have hands with fingers to grab?

http://en.wikipedia.org/wiki/Parasaurolophus#mediaviewer/File:Parasaurolophus_cyrtocristatus.jpg I cannot tell if the hands have fingers strung together to form a hove, or fingers to grab. I have ...
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The skin color of bonobos

Why is that bonobos skin color on the areas not covered by hair are dark throughout life unlike the chimpanzee?
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Evolutionary reasoning behind redundancy of CST and RuST

According to my neuro-anatomy class, both the Corsticospinal Tract (CST) and the Rubrospinal Tract (RuST) control upper limb movement. What the evolutionary reasoning behind this redundancy and the ...
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61 views

Evolution of sexually concordant genetic variation on the X-chromosome

It was theorised in 1984 that sexually antagonistic genetic (SA) variation should more easily evolve on the X-chromosome. This is partly because female beneficial/male deleterious mutations face less ...
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110 views

Can human change its morphology or anatomy due to ecological changes?

According to Charles Darwin, as the surrounding environment changes, so changes the anatomy or morphology of a specific organism. But nowadays, humans have become very advanced in the technology and ...
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How important is the womb's environment?

- Background - Talking about one phenotypic trait, the total phenotypic variance $V_p$ is decomposed into genetic and environmental variance for this trait, represented by the symbols $V_G$ and $V_E$ ...
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Propagation of tool use in primates?

There are several famous cases of great apes demonstrating a surprising degree of wherewithal in communication and tool use - even monkeys can learn some tool use from each other observationally, even ...
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Triune brain model

I have heard about the triune brain model in biology class, but my teacher does not know much about it. What I'm curious about, is this model accepted by most of the neuroscientists, or is it just a ...
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576 views

Cambrian explosion and evolutionary arms race

I've seen many times mentioned in textbooks and popular articles that a reason of the Cambrian explosion is an 'evolutionary arms race' between predators and prey. But this isn't really a sufficient ...
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Is there any evidence for sperm parameters being connected to fitness of the offspring produced by that sperm?

In most (if not all) sexually procreating species the amount of offsprings a male can produce is limited not by the amount of sperm he can produce, but by the amount of eggs his sperm can fertilize (...
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199 views

Why are mules/donkeys aggressive when faced with predators but horses are not?

I came upon an interesting quote after going down the rabbit hole on a variety of subjects. While deep in the data, I came upon this quote oat and farm animal owners likes to have mules with their ...
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Why does the cyclic flow of electrons in photosynthesis stop the production of oxygen?

Why does the cyclic flow of electrons in photosynthesis stop the production of oxygen? Is there some type of feedback mechanism at work here? The water molecule being split means an oxygen atom and 2 ...
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Why mammals don't have renal portal system

I am a high school student and I am a little confused why mammals don't have renal portal system?, some books says that because we have four chambered heart, so our blood is filtered more effectively ...
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How did humans evolve to appreciate Entertainment? What role does Entertainment have in survival and natural selection?

Humans appreciate sports (watching) and entertainment (arts, palys, movies, etc.) I am not sure if other animals can appreciate watching sports or other forms of entertainment. I am wondering what ...
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Did snow leopards loose the ability to roar or never have it?

Since snow leopards are the only species in the genus Panthera that can't roar, was this something the others developed after snow leopards diverged or something that snow leopards lost?
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Did mammals evolve from something with eusociality?

Eusociality (from Greek εὖ eu "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of ...
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Is artificial selection a mechanism of evolution?

From whatever I read have seen that the mechanisms of evolution are natural selection mutation genetic drift, and gene flow But artificial selection is often taught like a separate subtopic, but ...
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How did Rna replicate according to Rna World Hypothesis?

I was studying Rna World Hypothesis in Khan Academy, and there is a line..... The RNA world hypothesis suggests that life on Earth began with a simple RNA molecule that could copy itself without help ...
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Has the human capacity to heal from burns evolved due to actual burns throughout human history?

I just burned myself while cooking, and it occurs to me that although this has happened countless times, my skin always heals itself rather well after burns. In this post I make various assumptions/...
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How did migrations evolve?

Disclaimer: I know nearly nothing about biology. I was wondering how did the migratory behaviour of birds evolve. Assuming that evolution/natural selection works slowly and gradually (at least most of ...
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Question relating to gradualism

Is phyletic gradualism and gradualism essentially the same thing I just saw the term phyletic gradualism and I was wondering
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Can bacteria (dis)assortatively mate?

After revising some evolutionary concepts, I stumbled on the "big five" of evolution (e.g., mutation, selection, mating, genetic drift, gene flow). I wanted to understand if mating as in &...
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Do uerotelic organisms save roughly 3/4ths water compared to ammonotelic?

My analysis based on Daniel Atkinsons work, professor in biochemistry (see references below), is that ureotelism is saving 3/4ths water compared to ammonotelism. Is this correct? What do people here ...