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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Why did the urinary bladder evolve?

Sure it's convenient to decide when to urinate but not essential for survival or reproduction, as I understand. But just convenience is not a drive for evolution. Does the bladder serve any essential ...
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0answers
27 views

Brain capacity of Cro-magnon man vs Modern man

Cranial capacity of Cromagnon man was about 1650cc whereas average cranial capacity in modern human is 1450cc. My question is, why during the course of evolution, a reduction in cranial capacity is ...
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Why were dinosaur skeletons so light compared to mammal skeletons?

I was watching a presentation by Dr. Jessica Theodor [1] who discusses (at 38:10), among other things, the skeletal structure of dinosaurs vs. mammals. "Dinosaurs have way lighter skeletons, which ...
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25 views

How were (many) dinosaurs' brains so small?

Brain size (or its proxy, encephalization quotient) usually varies allometrically with mass -- larger creatures need larger brains to control their larger bodies, apparently. Dinosaurs are popularly ...
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If oxygen is such a good energy source, why do plants release it?

Why do plants release excess oxygen, rather than consuming it entirely given it is an excellent energy source?
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4answers
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Why would a plant evolve to produce an addictive chemical?

It seems kind of anti-productive in terms of survival for a plant to produce an addictive chemical as that plant will constantly be sought after by animals that ingest it. In this instance, I'm ...
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2answers
55 views

Current scientific theories for evolution of Cucurbita

I'm attempting to find research on scientific theories surrounding the evolution of certain plants, and am unable to find any footing with respect to a certain genus. In this case, I am researching ...
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78 views

Does cancer cells come from same process as evolution? [duplicate]

Here is how I understand it: DNA replication is not 100% perfect and error can happen, this error can be good(evolution) or bad(cancer properties). But its not the only source of cancer cells - DNA ...
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1answer
34 views

the evolution of the human brain size [closed]

I was thinking, as I know, sometimes the process of producing DNA did not work well(correct me if I'm wrong), so it gives us some changes in the object we gonna ...
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2answers
118 views

Are humans evolving since their first appearance? [duplicate]

Is the evolution a very prolonged progress, or are we going to witness further evolution of the human species? If so, in which direction? Are there any widely predicted changes for humans?
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3answers
526 views

Genetic Diversity and Adaptation

I am somewhat new to evolutionary biology, having studied it on my free time as a computer science student. There is one particular thing that has always bothered me for which I have not seen a good ...
7
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1answer
112 views

Why do fetuses have membranes between fingers and toes?

Are the membranes present between the fetal fingers and toes a remainder of the phylogenetic evolution, or just a way organs do grow most easily?
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2answers
922 views

Viral Mutation Mechanism

I think I have a wrong concept about viral mutation process. First of all what is mutation actually? I mean, I know it's a sudden change in DNA, happening when subjected to mutagenic agents. But can ...
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5answers
485 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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1answer
84 views

How do minute changes in an organism, as a result of evolution, get carried over to next generation

The theory of evolution states that random variations in organisms occur to better suit their surroundings. We take for example a bacteria's flagella. There's a bacteria who has a tube kind of ...
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75 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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2answers
192 views

How to define “evolution”?

The standard answer to the question: what is evolution? is: It is a change in allele frequency over time! I believe a complete definition should encompass the following concepts: ...
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Why do some bad traits evolve, and good ones don't?

If a trait would be advantageous to an organism then why hasn't it evolved yet? Conversely, if a trait is not advantageous or mildly disadvantageous, why does it exist? In other words why does ...
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0answers
176 views

What traits make mountain goats so well adapted to mountain living?

I've never really understood how mountain goats manage to survive so well in mountainous regions. I've seen them scale almost sheer cliff faces with apparent ease, and they can almost sprint ...
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1answer
150 views

Can we say the 'goal' of Mullerian mimicry is a 'decrease in the number of sacrificed indivials'?

Can we say that Mullerian mimicry allows two species to decrease their number of sacrifice individuals because: Originally, one species needs to sacrifice some individuals to allow predators to ...
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1answer
39 views

Is there any evidence that any other species are “pre-intelligence”? [closed]

Is there any evidence regarding whether other species might, given time, evolve intelligence as humans have? I realize "intelligence" is a vague word here, but I'm interested in throwing a wide net, ...
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1answer
34 views

Does the species of snake that eats Amphidromous inversus have chiral dimorphism?

From what I read at Schilthuizen and Davison (2005), Amphidromous inversus is a species of snail that occurs in 2 forms that are nearly mirror images of each other occurring in nearly equal ...
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460 views

Why don't rats have a gallbladder, unlike other rodents?

It has long been known that rats do not have a gallbladder, though other species including humans, monkeys, cows, reptiles, dogs and mice, all have a gallbladder. In this paper from almost 100 years ...
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6answers
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Why are there no organisms with metal body parts, like weapons, bones, and armour? (Or are there?)

Reading this question, Why are there no wheeled animals?, I wondered why no organisms seem to make use of the tensile and other strengths of metal, as we do in metal tools and constructions. I am ...
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37 views

Origin of aerobic respiration [closed]

Since life originated in water, did the first eukaryotic organisms utilize the dissolved oxygen in the water or they respired anaerobically?
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0answers
23 views

Describing trait evolution across a very small phylogenetic tree [closed]

I am very new to phylogenetic comparative methods but I want to explore the evolutionary patterns of a number of quantitative traits I have across a small sample (5) of closely related species ...
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5answers
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Why do living fossils like crocodiles remain so constant and not evolve? [duplicate]

Crocodiles have supposedly remained unchanged for millions of years, and several other species are considered as "living fossils". How do such species remain so constant over time given that they will ...
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How much of the genetic differences between humans and chimpanzees are due to genetic drift?

Both natural selection and genetic drift play a part in changing our DNA over time. Are there trustworthy estimates how much of the differences over the whole genome between us and chimpanzees are due ...
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84 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 ...
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1answer
50 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 ...
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1answer
59 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 ...
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0answers
85 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 ...
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3answers
163 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?
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4answers
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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 ...
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328 views

How did zootoxins evolve?

I've always wondered how toxins in certain organisms have evolved. Particularly, organisms that produce toxins as a deterrent to predators as opposed to organisms that use it to paralyze their prey. ...
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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, ...
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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 ...
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2answers
306 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 ...
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52 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 $t$ ...
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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 ...
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2answers
338 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 ...
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3answers
357 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 ...
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2answers
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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
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1answer
216 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
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646 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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 & ...