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 do men have nipples?

I'd be tempted to call nipples in men vestigial, but that suggests they have no modern function. They do have a function, of course, but only in women. So why do men (and all male mammals) have them?
3
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5answers
1k views

How did the cardiovascular system evolve?

I am very interested in chemistry and biology and one of my questions is: How has evolution created our bodies or rather the blood, lungs and the heart? Because we can't exist without blood, which ...
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1answer
49 views

How do poikilotherms thrive in a wide range of core temperatures?

What is it about the metabolism of a poikilotherm that enables them to adapt to the surrounding temperature?
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3answers
2k views

How do we know that our genetic similarities to other species is actually due to common ancestry?

I know all about how the fossil record shows more human-like species coming about over time, and how modern testing proves we have genetic similarities with other animals. All that says is we have ...
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0answers
69 views

evolution in such a short time? (history is too short for DNA base mutation + natural selection to result in current vast number of species) [duplicate]

Apart from my being a Christian, I have this strong suspicion that evolution must be wrong. One of the clues is the mismatch between the past time lapse and the current level of evolution. I'm not a ...
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1answer
56 views

How can evolution make such complicated beings?

So what I understand is, evolution is a mere mistake in the replication of DNA and this change is sometimes good and sometimes bad. And the other day, in our biology class, we were told the ...
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1answer
24 views

Is our genetic evolution driven by what we catch? [on hold]

When an environment changes, a multi celled organism can lose some cells without it producing an equal evolutionary change. But when a single cell organism experiences the same environmental pressure ...
3
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3answers
94 views

Real-world examples of Darwinian extinction

Darwinian extinction (also known as "evolutionary suicide") refers to processes of selection-driven self-extinction, i.e. the cases where natural selection causes the extinction of an evolving ...
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1answer
87 views

Mutations, Death and the theory of Evolution [on hold]

Evolution always made sense to me and I still find it to be true. However, I quite recently found a comment online that gave me some doubts and made me curious on the subject. Although a student of ...
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0answers
22 views

What reason that land vertebrate evolve keratin while other animal use chitin

I don't know why there are evolutionary split in material. Why we evolve keratin and lose chitin? What the advantage and disadvantage for each material? Is it because the size or there are other ...
0
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1answer
48 views

Why aren't all animals cold blooded?

At least, why don't all animals produce no more heat than the tiny amount that's a byproduct of walking or a bonobo climbing up a vine when the outside temperature is above 0°C? They won't freeze ...
0
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1answer
65 views

What did young pre-mammals eat before milk evolved? [on hold]

Mammals tend to be born helpless and teeth-less (and in some cases, blind). So for the first periods of their lifetime, they drink milk. Before this milk-producing property was evolved, what did the ...
1
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1answer
23 views

Which magnoliophyta groups are NOT pollinated by bees and why? [on hold]

Considering the bees as the family Apidae which families of flowering plants are definitely not pollinated by them and what could be the reasons? -Could you say that the relationship is preserved at ...
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1answer
61 views

What are Some Classical Examples of Local Adaptation?

Question Can you please give a list of classical (textbook) examples of local adaptations? How to answer Examples don't necessarily need to include what evidence supports this specific example of ...
3
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1answer
125 views

Why is the manchineel tree so poisonous?

The machineel tree is incredibly toxic to humans. What advantage could Hippomane mancinella have for being so poisonous? It's name even apparently translates to “little apple that makes horses mad”. ...
0
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0answers
35 views

What are some explicit examples of natural selection's predominat role in the origin of new species? [closed]

I am taking an evolution course and I found examples in textbook that include examples of organisms that came into form long, long time ago. I could not directly relate their formation to natural ...
0
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0answers
32 views

Are antibiotic-resistant bacteria necessarily less virulent than their original strain?

In the absence of antibiotic treatment, is there a reduction in the average severity of disease caused by resistant strains of pathogenic bacteria compared to wild-type ones? I would assume that ...
0
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1answer
34 views

How diverse are species in remote, isolated areas on Earth? [closed]

If we consider land areas that have been largely isolated from each other from a human point of view, but with a similar climate – for example, a part of Europe and a part of Americas with a similar ...
0
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1answer
64 views

Evolution to store limited Fat

Why are our bodies not evolved to store only limited amounts of fat, which won't kill us with all diseases associated with obesity? Wouldn't obese people die faster and clean the gene pool for people ...
1
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1answer
30 views

What factors make a sequence evolve non-randomly?

On the wikipedia page about Fay and Wu's H, it talks about a non-randomly evolving sequence may be due to some selection acting or a selective sweep or population expanding/contracting. My questions ...
2
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1answer
57 views

What contributes to the variation of protein sequence across different species?

What contribute to the variation of protein sequence across different species (e.g. phenotype, environment, evolutionary pressure) and how do those factors contribute to the variation? I have tried ...
1
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1answer
64 views

Symmetry in animals [duplicate]

Is symmetry in animals due to DNA or natural selection? By symmetry, I mean the left side is an almost (not perfect) reflection of the right half. Is this due to DNA trying to balance the two half or ...
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0answers
17 views

Were Neandertals as Hairy as We Are?

What I mean to say regards facial and androgenic hairs. There are many theories as to why some people have both kinds of hairs, while others have one or the same and others still have neither. The ...
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0answers
37 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. ...
2
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1answer
47 views

Identity By Descent vs Identity By State

Background The concepts of Identity By Descent (IBD) vs Identity By State (IBS) are central in population genetics, yet I fail to fully wrap my head around the definitions. You can find examples ...
3
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1answer
42 views

What negative effects does cannabalism have in other species (like prion diseases) and how are they mitigated?

It is well known that human cannibals are likely to suffer from a variety of ailments, particularly prion diseases. However a great many other species, from insect to ape practice cannibalism at much ...
11
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1answer
682 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 ...
3
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2answers
47 views

Does an increased reproduction/mortality rate provide an evolutionary advantage?

If a species has a high mortality/birth rate, then it is able to adapt to changing environments more quickly than species that live for a long time. Without a high mortality rate, food and other ...
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3answers
388 views

Where are the evolutionary “inbetweeners”? [closed]

The problem I've always had with evolution is the actual lack of variation between animals. More specifically, the lack of observable gradual change between species. Take for example the hammerhead ...
38
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5answers
12k views

Why don't mammals have more than 4 limbs?

Arthropods have 6 or more limbs and arthropods with 6 limbs appear to move faster than arthropods with 8 limbs so I wonder whether this might have something to do with fast and efficient locomotion. ...
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1answer
18 views

Are fish averse to extreme heat?

Terrestrial animals face two common sources of heat extreme enough to pose a danger to them: Sunlight and fire. It therefore stands to reason that they would evolve systems for sensing heat and ...
1
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1answer
33 views

Is it possible to have a random un-mutation of genes?

According to this article: Gene mutations can be classified in two major ways: Hereditary mutations are inherited from a parent and are present throughout a person’s life in virtually ...
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0answers
16 views

Is every evolutionary change an improvement? [duplicate]

In evolution, an species mutates and evolves over large genetic time spans. But every big change (say, swimming to walking, or walking to flying) is made up of countless micro-changes over the course ...
5
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2answers
66 views

Is there more diversity in marine species?

I was reading about how life emerged from oceans, and the following question occured to me. Do land species suffer from the founder effect and is there more (genetic) diversity in marine species? A ...
2
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1answer
59 views

What does completing the course of antibiotics accomplish?

This article from the WHO states: If you stop treatment early, there is a risk the antibiotics won’t have killed all the bacteria that made you sick and that it will mutate and become resistant. ...
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0answers
19 views

Are there observed instances of genes expressing undesirable traits to dissuade members of a particular species from reproducing?

All living things on earth are programmed to both survive and reproduce, but are there observed, documented or otherwise novel cases where the genes of any particular member of any particular species ...
0
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0answers
48 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 ...
5
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2answers
98 views

Relationship between lifespan and reproductive age?

I remember reading a while ago that there is a "general rule" in biology between an animals lifespan and when they reach reproductive age. In other words, an organism that reaches sexual maturity ...
1
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1answer
54 views

In Darwinian evolutionary theory, does the environment has any role? [closed]

In Darwinian evolutionary theory, does the environment has any role? To state it clearly: Suppose I have an isolated system. First, I place several types of entities (organisms) in an environment. ...
0
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1answer
65 views

How did humans in different regions evolve so differently? [closed]

Google is about as helpful as a mouse trying to catch a piano, since it's listed websites that aren't very clear or informative. So: How did humans evolve to be so different from one another? Say, ...
6
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1answer
90 views

Understanding F-statistics in population genetics

I am reading a classical Weir and Cockerham 1984 paper about Fst estimation. At the beginning (first page, right column), they define 3 statistics. $F$ is the correlation of genes within individuals ...
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0answers
15 views

What are chemical candidates for replicator molecule?

I have read Selfish gene by Richard Dawkins and idea is that at random some molecule was synthesized that had a property if there is enough 'materials' to construct ...
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1answer
71 views

What is the evolutionary advantage of having pubic hair?

Only humans have pubic hair. What is the evolutionary advantage in having it?
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1answer
68 views

When did death due to aging first appear? [duplicate]

As I understand it, single-celled organisms that reproduce via mitosis essentially live forever. When a cell divides, one cannot say that either one of the new cells "is" the parent and the other the ...
2
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1answer
104 views

Why did we evolve to control our breath?

I had this question in my mind and tried to think of why we would evolve to be able to control our breath. I remembered the Aquatic Ape Hypothesis, which makes a lot of sense and would explain it, ...
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1answer
70 views

Why do people find anal sex pleasurable? [closed]

First of all, anus is not a genital part like vagina and therefore pleasure due to anal sex should not have any fitness advantage. I wish to know why many people find anal sex pleasurable when it ...
11
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1answer
3k views

Why are some berries poisonous?

In my understanding, the evolutional function of berries is to be eaten and pood out somewhere else, so that the seeds of the plant spread. Is this so? Then why are some berries poisonous?
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2answers
64 views

What is meant by topographic barrier?

There are three types of barriers, physical , climatic and biological barriers that can prevent the dispersal of organisms. Topographic barrier falls in the category of physical barrier but exactly ...
0
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0answers
32 views

Why people have less hair than other primates? [duplicate]

Well as you can figure out, most primates such as monkeys, gorillas and chimpanzees, have all their body covered with fur. As we know they are evolutional "relatives" to us humans, but we dont have ...