The Time Machine (2002 film)
2002
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Learn how natural selection is a mechanism of evolution and how species adapt to their environment through variations in traits. Watch examples of natural selection in action, such as the peppered moth, the flu virus, and antibiotic-resistant bacteria.
- 18 min
- Sal Khan
- Just curious, are viruses living?Viruses are a borderline case but generally are not considered to be alive. Although they contain DNA (or RNA), they lack the machinery to replicat...
- I have a quick question. Why do species vary? For example why are some people taller or shorter than...This is a good question :) I'd like to explain it from both a technical and practical point of view: Technically, lets say that maybe once upon a t...
- What causes these "random mutations"? Has this been answered or it is still a mystery of the univers...There are 3 ways a mutation can occur unfortunately I wouldn't feel comfortable going too indepth as I don't know it will enough to explain each st...
- Why aren't there animals that are in the middle of different stages of development?I'm not quite sure what you mean by "in the middle of different stages of development". I guess from the context, you mean in the process of evolvi...
- Would it be accurate to think of evolution as being similar a game of telephone? As a word is passed...Yes, You can say in that game of telephone, that 'natural selection' would favor a word that very easy to pronounce and not very prone to being mis...
- Whats an RNA ?RNA is Ribonucleic-acid. It is a polymeric molecule made up of one or more nucleotides. A strand of RNA can be thought of as a chain with a nucleot...
- Do we (by "we" I mean science) actually know what causes the changes ? Because, as the bacteria exam...Very good point Daniel. The resistant bacteria did not always exists. 2 important things to know about bacteria: 1. Due to the simple nature of bac...
- why do we fall ill?Because another organism bent on benefiting itself at our expense has taken root inside our body ex, the cold or the flu. Sometimes we fall ill bec...
- Can you give us some mammal or plant examples of natural selection?Miyanda - your example is a good one, but a bit oversimplified. The Native Americans did have an immune system - all humans do. It was actually the...
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When did human evolution begin?
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Learn about evolution and common ancestry with this video from Khan Academy, a nonprofit organization that provides free education for anyone, anywhere. Watch the video, read the transcript, and join the conversation with other learners and experts.
- 4 min
- Khan Academy
- How did the world begin?Your answer depends on what you mean by "world". If you meant the universe: The universe (space, time, matter, energy, etc.) all began with the Big...
- What is the weirdest theory of how the universe was made?There are some weird theories out there, but the one I think seems to be the most implausible yet very fascinating is the big bounce. It explains h...
- how did the world begin ?I think it’s something called The Big Bang theory.
- is there a theory for how objects that were there in big bang theory came to be?The big bang describes how the universe began, so I guess the universe itself could be the only object that's directly "in" the big bang theory. Ar...
Hank gets real with us in a discussion of evolution - it's a thing, not a debate. Gene distribution changes over time, across successive generations, to give rise to diversity at every level of biological organization.
Oct 19, 2023 · The story of human evolution began about 7 million years ago, when the lineages that lead to Homo sapiens and chimpanzees separated. Learn about the over 20 early human species that belong in our family tree and how the natural selection of certain physical and behavioral traits defined what it means to be human.
