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Ancient Ancestors Had More DNA Than We Do Now: Have we Devolved?

Have we Devolved?


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Kashmiri Pandit

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Adding to the number of unsolved mysteries regarding the ancient origins of humanity and the biology of our species, scientists have discovered that we have less DNA now than our ancient ancestors possessed. Are we de-evolving?

A study published this week in the journal Science has found that modern humans lost DNA as we evolved after our split from apes. Our ancient ancestors, early humans, possessed substantially more amounts of genetic data than we do now. This surprising discovery raises many questions, the most obvious one being: why did we lose all that genetic information? Also, what difference has the loss made?

The short answer is: we don’t know yet.

According to news website Gizmodo, the team of researchers led by Professor Evan Eichler, geneticist at the Department of Genome Sciences, University of Washington, sequenced the genomes of 236 individuals from 125 distinct populations. They found that Homo sapiens have shed approximately 40.7 million base pairs of DNA after breaking from our closest living relatives, chimpanzees, around 13 million years ago.

Map-of-the-125-populations.jpg


Map of the 125 populations sampled in the study and their relation to each other. (P. Sudmandt et al 2015)

The genome of modern humans now contains 3 billion base pairs of DNA (complex molecules which contain all of the information necessary to build and maintain an organism, the building blocks of life), and even then scientists are unsure how much of that number is so-called “junk DNA”—genomic data whose function, if it has any, is not understood—but they do assert that at least 27.96 million of the base pairs lost were unique.

DNA-deletions.jpg


Common relationships were traced via DNA deletions among groups of humans. The longer lines show groups with more missing DNA. (P. Sudmandt et al 2015)

Have modern humans beneficially shed superfluous DNA, or have we lost something important over the generations?

Eichler proposes that a migration out of Africa reduced the human population in new areas and played a role in the loss of DNA.

Study authors write, “the breadth of the dataset allowed us to reconstruct the structure and content of the ancestral human genome prior to human migration and subsequent gene loss.’

‘As expected, Africans were more likely to show evidence of these ancestral sequences compared to non-African populations, as the latter have experienced more population bottlenecks and thus retained less of the ancestral human diversity.” Meaning that those individuals who were more connected with Africa had retained more DNA than those who had descended from migrated populations.

MailOnline reports, “The human genome has around three billion base pairs, which reside in 23 chromosomes in the heart of almost every cell in our body. The average gene in the human genome is around 765 base pairs long, meaning humans could have lost the equivalent of up to 37,000 genes since splitting from our ape cousins.”

Adding to this mix is the historic breeding of modern humans with the now extinct Denisovans and Neanderthals. Segments of Denisovan and Neanderthal DNA can be identified now in modern populations. But Neanderthals and Denisovans had around 104,000 base pairs in their genomes that are not found in modern humans. Researchers found that Neanderthals and Denisovans were missing some ancient DNA as well, suggesting these extinct species had lost significant portions of genetic code.

“Their results showed that our ancestors shed about 15.8 million base pairs of DNA before leaving Africa. As populations spread across Earth’s continents, they jettisoned additional chunks of DNA here and there. But certain populations have also been gaining DNA, mostly through duplication events where portions of the genetic code were accidentally copied and passed on,” reports Gizmodo.

While modern humans may presume that the shedding of DNA has honed us to the peak of evolutionary perfection, science can show that not all of our changes have been beneficial. In one example, research suggests that our hands are actually more primitive than those of our chimp ancestors, despite our adaptations for the use of tools.

Chimpanzee-hand.jpg


Chimpanzee hand, at left, and human hand, right.

This is the first time scientists have documented the loss (and gain) of large chunks of DNA in ancient populations. This genetic research may shed light on the enduring questions of how modern humans evolved and survived while other hominin died out.

Scientists still can only speculate as to what these results indicate, but as more research is done we can fill in the missing gaps of our understanding of the ancient story of humanity.
 
The man upstairs is just playing a big joke on us.

THE END.
It is proved long back that not only the genetic codon, but the protein also have very significant role in critical biochemical procedure of cell. A specific codon only attach a particular amino acid into a growing polypeptide chain (which is fixed for all eukaryotes), but the real difference is made in the structural diversity(primary, secondary, territory or quaternary, branch, sheets or chains), folding and clipping of the newly synthesized protein. And many nonsense codons are also deleted during the process of evolution.
 
does that not happen in other species ?

I mean the dna that gives an organism the highest chances of survival is the one that goes on. Individual organisms with dna that is not as likely to survive just dies out. It's like fine tuning. The useless bits have been shaved off...
 
It is proved long back that not only the genetic codon, but the protein also have very significant role in critical biochemical procedure of cell. A specific codon only attach a particular amino acid into a growing polypeptide chain (which is fixed for all eukaryotes), but the real difference is made in the structural diversity(primary, secondary, territory or quaternary, branch, sheets or chains), folding and clipping of the newly synthesized protein. And many nonsense codons are also deleted during the process of evolution.

Do you speak english ? :blink: :(
 
Like in everything, size doesn't matter but the functionality is. When will we understand that?

Wanna see a specie that has a huge number of chromosomes?

Ophioglossaceae - Wikipedia, the free encyclopedia

It's a plant. Yeap you don't become an alien or x-men with more chromosomes. You can be a plant :)
 
Do you speak english ? :blink: :(
What is the relation of this topic with my native tongue?

i think we are reducing unecessary features
There is innumerable point mutation going on...it's a dynamic process.....there are many protective countermeasures running into the cell also to prevent them....like 'proof reading activity' of DNA polymerase II, p53 protein, telomeres etc....but they can't keep the process free from these point mutations everytime....specifically in a rapid cell division. Most common example of this mechanism is activation of proto oncogenes and transformation of a cell into malignancy.
 
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It's like fine tuning. The useless bits have been shaved off...
Exactly my thoughts!!!
The part which becomes obsolete and is not required any more, is removed from the system. This is how we evolve.
 
Do you speak english ? :blink: :(
it is certainly not greek or latin , i dont see alpha,beta, gamma or phi that would have made it even more interesting.:p:

Exactly my thoughts!!!
The part which becomes obsolete and is not required any more, is removed from the system. This is how we evolve.
Not exactly, only thing that seems to evolve now is our intelligence. One reason is humans tend to create/modify habitats suitable to them instead of adusting to it. We are simply fine tuning the env we live instead of body.

You can live in a desert or snowy land but still work in 25Celsius cooled env. If the entire area gets flooded you wont evolve gills but instead end up being on a boat. There will come a time when humans can no more cheat the nature. We have a price to pay like dinosaurs did.
 

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