The Recapitulation concept is interesting to consider. A vertebrate organism starts out as a zygote and goes through its fundamental phylogenetic history. One cell. A multicellular cluster (blastula). The five digit plan for the distal part of the appendage becomes one digit in perissodactyls, example, the horse. The concept was found to have shortcomings but it is still one of the fundamental biological concepts.
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BR: Ummmmm.... A - T - H - E - I - S - T. Atheist. People who do not believe in God or gods. Have you considered https://biology-forums.com/
@Cognostic
Thanks. I will check it out.
Re: OP
...*staring blankly at text*.... What... in.... the... hell... does ANY of that mean???... *scratching head in total confusion*...
@Tin-Man
It means that an organism goes through its evolutionary history during its embryonic development.
I have always been attracted to the mutation of polydactyly...look up 6 fingered people.
One more way how God works mysteriously.
Don't worry yourself about it Tin. Have another crayon.
@Grinseed
Hexadactyl! It makes you wonder? The pentadactlyl limb is such a rock solid basic plan in vertebrates.
Here is an excerpt from https://sites.google.com/site/darwinspredictions/the-pentadactyl-structu...
The pentadactyl pattern and common descent
The pentadactyl structure—five digits (four fingers and a thumb for humans) at the end of the limb structure—is one of the most celebrated proof texts for evolution. The pentadactyl structure is found throughout the tetrapods and its uses include flying, grasping, climbing and crawling. Such diverse activities, evolutionists reason, should require diverse limbs. There seems to be no reason why all should need a five digit limb. Why not three digits for some, eight for others, 13 for some others, and so forth? And yet they all are endowed with five digits. As Darwin explained, “What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include similar bones, in the same relative positions?” (Darwin, 382)
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In his book 'Endless Forms Most Beautiful' Sean B. Carroll details, in the popular form of science education, the genetic causes of polydactyly.
The set of genes found in the DNA of every living organism, often referred to as the Homeobox, controls the development of every part of the animal in question during foetal patterning, development and later, in growth and ageing. The Homeobox is a toolbox of different kinds of protein linked contigously on a single chromosome.
These proteins have attracted exotic names. One protein group in particular is called the hedgehog. In veterbrates there are three types of hedgehog: Sonic, desert and indian. Without going into too much detail as this is just forum reply, its the sonic hedgehog protein that regulates the development of limbs and digits. Polydactyly occurs as a mutation during the formation of the hand in humans during foetal development. The mutation occurs when the hedgehog protein misses out on the signalling to tell it to stop making fingers after number 5.
Six fingers (five fingers and a thumb)are the most common outcome but there are other types. (Google '6 fingered people')
For more mind blowing detail, read the book.
@ Tin, you will be pleased to know there is an important protein called "Tinman" that plays an important role in the formation and patterning of human and fruitfly hearts.
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