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stated clearly presents What caused life's Major evolutionary transitions? When looking at the fossil record and trying to list the most significant events in our evolutionary history You might want to list the earliest known fish species able to survive at least temporarily on Dry land You might also want to list the first known ape fossils which just like us appear to have walked on two legs While these fossils do represent fascinating transitions into new lifestyles
They don't represent large jumps in complexity the differences between two-legged and four-legged creatures Mainly come down to slight adjustments and how joints fit together [to] [see] a truly large evolutionary jump what researchers call a major evolutionary transition We have to travel back much further in the fossil record in the late 1830s anatomist Theodor Schwann Formalized the idea that the human body instead of being a single living thing is actually a collection of individual living cells
Today we tend to shrug this off as common knowledge, but think how amazing this is you are a Colony the earliest multi-celled animals found so far in the fossil record [were] primitive [sponge-like] creatures living in the sea Before them all living things. We know of were single-celled and came in three different types Bacteria and Archaea which both tend to be extremely [small] and then we have eukaryotes most of which are still microscopic
But far larger and much more complex than the others the cells that made up the first sea sponges and the cells that make up [your] body today are strikingly similar to single-celled eukaryotes [the] [main] difference is that your cells can no longer survive on their own? Instead trillions of them that's trillion with a t are all working together in near perfect harmony to make you you the move from single-celled creatures to multi-celled animals was a major evolutionary transition as a
Result your [body] now represents two distinct layers of life you as a whole and you as a colony bizarre as this fact is Are stranger things? inside the cells of all eukaryotes Single-celled and multi-celled there are tiny structures called mitochondria Scientists used to think these structures were simply body parts of the larger cell in the late 1960s However Lynn Margulis piecing together the discoveries of many others demonstrated
Beyond reasonable doubt that Mitochondria were once free-living Bacteria Mitochondria have their own genes they live reproduce and even die on their own inside their larger hosts Mitochondria feed on the nutrients our cells produce, but they are not parasites in Return for the food they consume they build and secrete special molecules called atp Molecules that our cells [use] as a source of energy kill the mitochondria and the larger cell will also die
This discovery means that you are not just two layers of life but three you as a whole you as a colony of cooperating cells and each of your cells as an interdependent community of Its own Profound as that is there's more inside Each of your cells in each of your mitochondria there is a genome a large collection of genes that together allow yourselves to grow
function and Reproduce in the early 1970s [Theodore] [döner] was investigating the cause of an illness in potato plants the culprits he discovered were the smallest simplest reproducing structures ever to be described He called them viroids. They are not cells. They are not even viruses instead. They are single free living genes Moving from plant to plant by hitching a ride on insects farming equipment or even a wind
Viroids use the chemistry and nutrients inside plant cells to [reproduce] the existence of free living genes strongly suggests that the genome of the first cells on Earth and By relation the genome in your cells today can actually be thought [of] as a collection of individual genes Working together in Cooperation in other words your body represents four layers of life you your colony of cells the many communities making up each one of your cells and
collection of genes that make up every cell's genome Each new layer of Life is the result of what scientists call a major evolutionary transition? What was the cause of these transitions the answer is? Cooperation a Major Transition starts when free living creatures team up to form a cooperative group in the early stages of cooperation Participants are free to come and go as they [please] [if] a group sticks together long enough however
Division of labor will often evolve different participants begin specializing in different tasks as time goes on Individuals may become so specialized that they can no longer survive on their own [if] the entire group becomes locked into cooperation Depending fully on one another to survive and reproduce a new super organism has been forged and they made your evolutionary transition is complete
From this point on the entire group will evolve together as one Models describing natural situations that might promote the evolution of major transitions have been put forth by scientists such as John Maynard Smith [fior] Sonck Mary stuart West and w d hamilton using these models Researchers have been able to Mimic natural scenarios in the lab Allowing us to directly witness the beginnings of major transitions [evolved] in
1998 researchers set up a mini Ecosystem with small mouths protists and single-celled algae the protists could easily swallow individual algal cells But had trouble eating cells that happen to stick together after reproducing in less than just 20 generations the algae evolved multicellular cooperation they form groups of eight tightly connected cells that could not [be] eaten by the protists [a]
similar experiment on single-celled yeast in 2011 Showed that [just] 32 days after multi-celled colonies evolved clear division of labor also evolved giving rise to unique cell types specializing in different tasks these two experiments show us how multi-celled organisms may have first evolved, but what about mitochondria and their permanent merger with eukaryotes In a long-term study ending in 2008 a protist that normally eats Bacteria was seen swallowing a species of algae
Apparently on accident that it was not able to digest Inside the protists the algae was able to grow and reproduce when the protists reproduced as well both daughter cells contained algae after several years and many many generations researchers found that when Bacteria was scarce Protists containing algae were much more likely to survive than those without They avoided starvation by feeding off the waste products the algae produced This was the start of a [Brand-new] relationship
Strikingly similar to what we find between [our] [cells] and the mitochondria [that] live inside So to sum things up what caused life's major evolutionary transitions the answer is cooperation major transitions begin when a group of organisms join forces to better survive and reproduce if cooperation continues long enough a new super organism may Emerge one that can then go [on] to reproduce and evolve as a whole and
The pathway that led [to] animals along with humankind [at] least three major transitions have been identified resulting in four layers of Life within your own body Experiments in the laboratory have allowed us [to] directly witness the beginnings of major new Transitions evolve. I'm John Perry and that's Major evolutionary transitions stated clearly This animation was based on a paper by stuart west and his colleagues called Major evolutionary transitions and individuality
In it stuart goes over the three transitions. I showed in this animation plus several others Certain insects like bees and ants have gone through an extra evolutionary transition. That humans never went through When you look at a colony of bees You're actually looking at a [superorganism] the entire hive reproduces and evolves as if it were a single living thing For more on that evolutionary transition check out the video produced by Oxford's brilliant and lovely anis [Dosan] hey
I'm an ace and my Youtube channel is draw curiosity So long for now stay curious you
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