Human evolution fast-tracked by mutations from anti-viral enzyme

[Plazma Inferno!]

Evolution is thought to proceed through the gradual accumulation of independent mutations in each new generation. In a new study, researchers analyzing hominid genomes have discovered thousands of clustered mutations likely resulting from the coordinated activity of APOBEC enzymes, leading to accelerated changes in DNA.
Mutations occur through a variety of mechanisms, including mutagenic agents such as ultraviolet radiation, and error-prone cellular processes such as DNA replication and repair. In cancer, it was recently recognized that mutations could occur as the result of human APOBEC enzymes, which deaminate cytosines and lead to many clustered base substitutions in DNA. Interestingly, the APOBEC family, and in particular APOBEC3, have dramatically expanded in copy number in primates. The expansion is thought to be in response to the emergence of primate-specific viruses, which APOBECs target for inactivation.

http://medicalxpress.com/news/2016-04-human-evolution-fast-tracked-mutations-anti-viral.html

 

[sculptor]

wow

 

[Write4U]

That sounds very interesting, but should that principle not hold for all organisms?
Any data on that?

IMO, the one single pure distinction betweenf humans and other primates lies in their chromosome count.

Whereas all primates have 24 pairs of chromosomes, humans only have 23 pairs. This was due to the fusion of two chromosomes in our ancestors into a single much larger chromosome, presumably with much greater potential inherent in the greater complexity of that specific chromosome which sets us apart from all other primates..

This article describes this phenomenon in detail:

Human Chromosome 2 is a fusion of two ancestral chromosomes,
All great apes apart from man have 24 pairs of chromosomes. There is therefore a hypothesis that the common ancestor of all great apes had 24 pairs of chromosomes and that the fusion of two of the ancestor's chromosomes created chromosome 2 in humans. The evidence for this hypothesis is very strong.

http://www.evolutionpages.com/chromosome_2.htm

IMO, if we want to look at the thing that sets us truly apart from the offspring of our common primate ancestor, this major mutation must have played a great part in the consequent evolution of Homo Sapiens.

 

[sculptor]

Question:
What do fast tracked mutations do to/for the assumed h s sapiens genetic bottleneck assumed to have been circa 70ka?
I believe that that date was based on an assumed steady rate of mutation.

 

[Walter L. Wagner]

That sounds very interesting, but should that principle not hold for all organisms?
Any data on that?

IMO, the one single pure distinction betweenf humans and other primates lies in their chromosome count.

Whereas all primates have 24 pairs of chromosomes, humans only have 23 pairs. This was due to the fusion of two chromosomes in our ancestors into a single much larger chromosome, presumably with much greater potential inherent in the greater complexity of that specific chromosome which sets us apart from all other primates..

This article describes this phenomenon in detail: http://www.evolutionpages.com/chromosome_2.htm

IMO, if we want to look at the thing that sets us truly apart from the offspring of our common primate ancestor, this major mutation must have played a great part in the consequent evolution of Homo Sapiens.

I made the same comment about two years ago in a different thread. That fusion event sets us apart from all others. I queried as to when it happened; clearly before development of H. sapiens neandertalensis.

 

[Write4U]

Question:
What do fast tracked mutations do to/for the assumed h s sapiens genetic bottleneck assumed to have been circa 70ka?

What does "circa 70ka" really mean when dealing with very large numbers? Remember, we are not dealing with "certainty or chance*, we are dealing with a range of probabilities, 10k more or less, is really irrelevant.

I believe that date was based on an assumed steady rate of mutation.

Mutations need not be DRASTIC. There would still be an evolutionary process, however our evolution now
included the added potential of the mutated genome.

We are still hominids, but instead of specialized skills in *adaption* to the environment. We learned to *create* our environment by our extra-ordinary *genetic code*.

btw, we are not the only species that use available resources to *create* an environment which is sufficient for their use. Birds especially have extraordinary skills in creating a *home*, even bee and termite hives have a built-in airconditioning system, spiders create a variety of means (webs, nets, ambush) for capturing prey, sea-otters use a *hammer and anvil*, to crack open *shell*, as do several ape species and birds with shelled fruits.

But to my knowledge humans are the only hominid sub-species which has a different genetic count (and genetic coding) from all other hominids as far back as our common ancestor. This makes us clearly different.

IMO, that scientific fact must have been instrumental in some way in the evolution of an advanced brain and ability for deep abstract thought in h.s. I would not necessarily call that "fast-track", but rather *expanded* evolution through a more sophisticated neural network in the brain.

In context of the OP, could this genetic change have been caused by the anti-viral event?

 

[sculptor]

The curious thing is that hominid brains rapidly grew in size until h.s.heidelbergensis a little more for h.s.neanderthalensis, then diminished for h.s.sapiens.
One might reasonably see that as de-evolution?
23 is a big question indeed.

The 70ka seemed to have been blamed on toba----------change the date of the bottleneck, and change the causal factor?

 

[Write4U]

The curious thing is that hominid brains rapidly grew in size until h.s.heidelbergensis a little more for h.s.neanderthalensis, then diminished for h.s.sapiens.
One might reasonably see that as de-evolution? 23 is a big question indeed.

Brainsize may not be indicative of greater intelligence at that time. Perhaps a more efficient *folding* might have given us the ability to squeeze more brain matter (surface area) in a smaller compartment.

The 70ka seemed to have been blamed on toba----------change the date of the bottleneck, and change the causal factor?

Perhaps there may have been several bottle necks. Migration along the west coast of Africa probably happened also and necessitated the development of different skills and tools. An western isthmus between Africa and Europe (Spain) may well have existed at that time.
This may clarify: http://www.humanorigin.co.za/pages/pinnacle-point/

 

[sculptor]

From your link:

“By correlating our knowledge of the climate with what we’re learning about the habits of the people who lived in the Caves, we hope to learn how humans can be expected to adapt to climate change in the future.”

amen
(except for the "lived in the caves" part----which I seriously doubt)
(recent evidence for neanderthals indicates that they built shelters, sewed weather-tight clothing, decorated their bodies, cooked vegetables, and engaged in art.) Archaeological evidence tends to remain available when sheltered in caves, which does not mean that that is where people habitually lived.

anecdote:
A tad over 37 years ago, I stood up in an anthropology seminar and declared that we could know little of the lives of the preceding subspecies unless we knew more about the climate in which they lived. --- which led to many a long days at the library---which led to the conclusion that we had very little knowledge of paleoclimates at that time. Much improvement has happened since that time. (yippee)
Which is why when Julie Brigham-Grette presented the Lake El' gygytgyn Research she became my favorite 50' tall woman du jour("shoulders of giants"):

(to my knowledge, the 1st mention of "superinterglacials)

Combining the Lake El' gygytgyn studies with that of Lee Berger has opened up a better understanding of our forebears circa 400ka.
.............................

Brainsize may not be indicative of greater intelligence at that time.

According to Lee R. Berger of the University of Witwatersrand, numerous fossil bones indicate some populations of heidelbergensis were "giants" routinely over 2.13 m (7 ft) tall and inhabited South Africa between 500,000 and 300,000 years ago.(including mis 11)
Wherein the largest brain cases were found--------(big people= big brains?)
or
Maybe they were more intelligent?
One long ago hypothesis was that large brain cases led to more difficult births led to smaller "natural increase" of populations? (So, we ditched the large brain cases in favor of more/easier births, and greater natural population increase? A woman thing?)

We have so little evidence upon which to hypothesize. Nice to keep finding more!

 

[origin]

One might reasonably see that as de-evolution?

Only if there was a goal of evolution is to have a bigger brain, which there isn't.

 

[sculptor]

Only if there was a goal of evolution is to have a bigger brain, which there isn't.

So, is there a "goal of evolution"?
If so, what?

 

[origin]

So, is there a "goal of evolution"?

No.
The goal of life is to survive long enough to successfully reproduce. Evolution is an outcome of that.

 

[Write4U]

Only if there was a goal of evolution is to have a bigger brain, which there isn't.

But there is a goal (impetus) for more efficiency in all areas, including the brain. Thus a more efficient brain folding, along with the loss of large jaw muscles and bone structure would be a natural evolutionary process, allowing for more space inside the skull, while maintaining a natural limit on the size of the skull itself.

As I understand it, Natural Selection most always selects for greatest efficiency in a smaller package, either with a *refined* specific adaption, or a greater "general versatility". h.s.s. seems to be a result of refined greater versatility in general, while maintaining the ability to produce offspring, through the development of a sophisticated mirror neural network, which can already be observed in other species in rudimentary forms. The ability to learn and remember what we have learned seems especially effective in humans. But the ability to count (cognition of the difference between size of quantity) is apparent in many species. The Lemur experiments in intuitive *counting* confirms that cognition of quantity was present very early in the evolution of species and perhaps the onset of *greed*, i.e. taking more than necessary and sufficient, except for storage in lean times, which is already seen in some insects which practice *agriculture* inside the hive to maintain sufficient food for newborns..

Why do squirrels store food ahead of necessity? IMO, that is a large question.

 

[origin]

But there is a goal (impetus) for more efficiency in all areas, including the brain.

I do not think that is accurate. Look at all of the ruminates, it is extremely inefficinet to eat grass. Many species have multiple stomache compartments to try and get the most nurishment from grass. Life will be as efficient or inefficient as necessary to utilize any niche available.

Thus a more efficient brain folding, along with the loss of large jaw muscles and bone structure would be a natural evolutionary process, allowing for more space inside the skull, while maintaining a natural limit on the size of the skull itself.

That process is only seen in people, if that was such a great efficient thing I would imagine we would see that process in most animals.

Why do squirrels store food ahead of necessity? IMO, that is a large question.

It is a behaviour that has helped to ensure their survival.

 

[Write4U]

I do not think that is accurate. Look at all of the ruminates, it is extremely inefficinet to eat grass. Many species have multiple stomache compartments to try and get the most nurishment from grass. Life will be as efficient or inefficient as necessary to utilize any niche available.

So, you answered your own question, except that currently living species are all efficient at survival "in their niche". That's why they are still around. Inefficiency eventually falls to natural selection.

That process is only seen in people, if that was such a great efficient thing I would imagine we would see that process in most animals.

That's where the chromosomal mutation played it's part. A drastic change in DNA instructions, which put our brain development on a *fast track*. And there are other such examples, except they were not always for brain development. But look at the cuttlefish. the smartest slug on earth, with multiple brains.

It is a behaviour that has helped to ensure their survival.

Which again proves, that what we may see as inefficient, is actually perfectly sufficient for survival. Could you live on grass alone? Millions of ruminants do. Proof of the successful (efficient) adaption to an abundant but hard to digest food source.

However, I will agree that no living organism is already perfect and all continue to evolve (through natural selection) for greater efficiency, but often retaining remnants of older (now useless) genes.

(Medical Xpress) -- Every person carries on average 100 variants that disable genes - yet very few suffer ill effects, an international team of researchers led by Yale University and Wellcome Trust Sanger Institute report in the Feb. 17 issue of the journal Science.

http://medicalxpress.com/news/2012-02-inactive-genes-surprisingly-common-humans.html