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Course: Middle school biology - NGSS > Unit 8
Lesson 1: Evolution and common ancestryEvolution
Review your understanding of evolution in this free article aligned to NGSS standards.
Key points
- Evolution is the change in inherited traits that occurs in a group of organisms over multiple generations. Inherited traits are those that are passed from parents to offspring via genes.
- Evolution is made possible by genetic variation, or gene differences, in a population. Genetic variation causes organisms within a population to have a range of different traits.
- One source of genetic variation is sexual reproduction. This type of reproduction causes offspring to have different sets of alleles (and traits) compared to their parents.
- Traits in a population can change over multiple generations of parents and offspring. New traits may arise. Or, existing traits may become more or less common. When this type of change has occurred, the group of organisms has evolved.
- Small differences between generations can add up. With enough time, evolution can give rise to new types of organisms. For example, over many generations, one species can evolve into two.
- Over the billions of years that life has existed on Earth, evolution has given rise to the amazing diversity of organisms on our planet.
Want to join the conversation?
- Is evolution intentinal? How do animals know how to evolve?(16 votes)
- Hmm, interesting question! I think it occurs naturally, as each species wants to survive.
The Snail Kite, a small predatory bird that lives in the Everglades, has a specially curved bill 'designed' to dig snails out of their shells. Around 2007, the island apple snail invaded the Everglades, wiping out smaller species of snails, for which the kite's bills were designed.
At this point, something called 'natural selection' kicked in. The snail kites with bigger bills could eat the new snails more easily, and therefore survived better. This led to the reproduction of more big-billed snail kites. In just 10 years or so, the entirety of the species had evolved to have larger bills so they could eat the big snails.
So, I think it happens naturally, without much brains involved. The individuals with better traits survive more easily, and therefore change the species in good ways.
Hope this helped!(39 votes)
- Is it just me or like the whole lesson all i could think about was Pokemon and the evolutions(22 votes)
- Same honestly.(6 votes)
- is the evolution only in animals or is it in humans as well?(5 votes)
- Evolution can happen in all living things. Not just humans and animals but also plants.(7 votes)
- what causes evolution(3 votes)
- A change in the environment around them, for example, maybe if a bird eats seeds but the shell starts to thicken, then they need stronger beaks.(8 votes)
- how can we be so sure of evolution? if we evolved from monkeys, than how come monkeys aren't still evolving?! I can understand adaptation, but evolution not so much(2 votes)
- We did NOT evolve from monkeys🙊(5 votes)
- Why does evolution take millions of years to happen?(2 votes)
- It doesn't have to take millions of years. For example, rattle snakes have evolved during the past few decades so that the rattle they have on their tails don't give a sound. It was to avoid hunters and to protect themselves, and now they are known as one of the typical examples of an evolution through only a few decades.(6 votes)
- how does this work(5 votes)
- Basically species evolve over time due to genetic variation and their environment through multiple generations. This causes species to branch into different species and evolve to Adapt to their environment through multiple generations and certain traits that enable the species to be more likely to reproduce will become more common.(2 votes)
- Can the animals be scared of their on type or a different blood(3 votes)
- ur an unneeded human being uncared about and unloved so shut up(1 vote)
- Do all organisms have evolution.(4 votes)
- no. In fact octopuses have no evolutionary ancestors(0 votes)