Science Notes: DNA on/off switch

The genome is the sequence of 3 billion molecules that constitute all of a person’s DNA. Nine-tenths of our genes are identical to that of a mouse. It doesn’t tell much. Neither would this: sixty percent of DNA found in the humans is also found in a banana. Where lies the mystery then?

DNA in a molecule is a genetic universe. A difference of .1 in a molecule would make some 3 million genetic differences.

According to recent discovery more light has been thrown into genes by comparing modern humans with the Neanderthal cousins. Present-day humans and their extinct Neanderthal cousins are 99.84 percent identical genetically.

Four years after scientists discovered that the two species’ genomes differ by a fraction of a percent, geneticists said on April 17,2014 they have an explanation: the cellular equivalent of “on”/”off” switches can activate DNA or silence genes. Hundreds of Neanderthals’ genes were turned off while the identical genes in today’s humans are turned on, the international team announced in a paper published online in Science. They also found that hundreds of other genes were turned on in Neanderthals, but are off in people living today.

That may explain anatomical differences between archaic and present-day humans, including Neanderthals’ shorter legs and arms, bowleggedness, large hands and fingers, and curved arm bones. Ancient humans were able to build stronger bodies, better adapted to the physical rigors of Stone Age life. And one might say body enhancing without using steroids or invasive surgeons knife certain genes were switched on. The discovery also underlines the power of those on/off patterns. Together, they add up to what is called the human epigenome, to distinguish it from the human genome.

Chief among the epigenetic differences: a cluster of five genes called HOXD, which influences the shape and size of limbs, including arms and hands. It was largely silenced in both ancient species, the scientists found.One person’s epigenome can vary markedly from another’s due to diet, environment and other factors. It is therefore impossible to know whether the on/off patterns found in Neanderthal genes are typical of the species overall or peculiar to the individual studied.

Other DNA with big differences in on/off patterns between the extinct and present-day humans is associated with neurological and psychiatric disorders including autism, schizophrenia and Alzheimer’s disease. More of the Neanderthal versions were silenced.

In an interview, Liram Carmel of Hebrew Uni., Jerusalem speculated that any given gene might “do many things in the brain.” When dozens of brain-related genes became more active in today’s humans, that somehow produced the harmful side effect of neurological illness.

But the main effect might have been the astonishing leap in brain development that most distinguishes modern Homo sapiens from our extinct cousins.

(ack: reuters/April 17-science)

benny

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Well of Time-2 Shaping emotions

First let me give opinions of an anthropologist and a biologist. ‘Our emotions make us unique 

While human aggression is a naturally evolved phenomenon we have in common with other animals, the difference between human and animal violence comes down to the complexity of the emotion driving it, said Elizabeth Cashdan professor of Anthropology of Univ. of Utah in 2009.


Aggression in few animals goes beyond protecting one’s territory, mates, offspring and food — there is some evidence that domestic dogs and chimpanzees do hold grudges, said Carrier, a Biologist also from Univ. of Utah — but human violence has evolved to stem from less typical sources.
“Humans are unique in the complexity of their social relationships and their highly developed social intelligence. Revenge and spite are quintessential social emotions and so are not likely to be found in many, if any, other species,” she said.
“For example revenge killings, and the cultural institutions that support and restrain it, 
shape human aggression in new ways,” said Cashdan. The intelligent reasoning that lets most of us override any innate desire to be violent also makes some people, such as parents that kill their children, as well as institutions justify violence illogically, experts say.
With our complex brain we splice frustration, fear for the future all the emotions violent and beautiful into shapes never thought possible. A chimpanzee can never commit hara-kiri a ceremony to wipe of dishonor. Whereas a man can flagellate for God or to show his intense sorrow for a dead saint.

Worry over the future



An understanding of the evolutionary roots of human aggression could help institutions make better policy decisions, according to experts.
“Evolution didn’t just shape us to be violent, or peaceful, it shaped us to respond flexibly, adaptively, to different circumstances, and to risk violence when it made adaptive sense to do so. We need to understand what those circumstances are if we want to change things,” said Cashdan.
Though conflicts like the ones that occurred in Rwanda and the former Yugoslavia in the 1990s may seem a distant memory, the tipping point between peace and that sort of violence is a finer line than we think, said Carrier.
“My personal opinion is that Western society, as a whole, is in mass denial about the magnitude of the problem that violence represents for the future”.
In a caste riddled Hindu society breaking rules of gotra the village elders may punish man and woman with death. If we consider such acts can only occur in a primitive society think of Grimmer of Texas, America.
Rachelle Grimmer, 38, pulled a gun on the welfare office supervisor, Roberto Reyes, and her two children out of her frustration at being denied food stamps. The office’s other employees were able to safely evacuate the building, according to the San Antonio Express.
A SWAT team surrounded the building, and officers communicated with Grimmer throughout the ordeal.
But at midnight — shortly after Grimmer hung up on police — three shots were fired, causing the police to storm the building.
(abc Good Morning America-7 Dec.2011)Frustration in progressive society is over future and in a primitive society is over the past. While we speak of superstition and ridiculous beliefs of the other cultures how we feel about future rely on the brain that is less than efficient. Our emotions we may shape into new forms but cannot escape the forces that bear upon the brain.
benny

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Circumcision

This custom of circumcision was practiced among so many widely separated race. Its object has been to diminish the sensitivity of the glans, no longer lubricated with prostatic lymph; thus the part is hardened against injury and disease. The practice goes far back in time and it has been noted in a mummy of xvith century BC. The Jews borrowed it from the Egyptian priesthood and made it in a manner of sacrament. Thus uncircumcised would mean heretic or barbaric. It became a seal of reconciliation between the Creator and His Chosen People. A separation was imposed upon the children of God by religion where the custom dictated from reasons of hygiene and prolongation of coitus. The cosmopolitan Romans had no use for this custom. The Jews use it figuratively as the ‘circumcision of fruits(Lev.xix.23),and of the heart (Deut.x.16). Patriarch Abraham did it when he was 99 also for his household (Exod. iv.25). The custom was suspended during the Desert wanderings and was renewed by Joshua(v.3-7),who cut off 2tons’ weight of prepuces. Compare it with the scalping of the American Indians or of the Scythians of old. King Saul promised the hand of his daughter to David for a dowry of 100. Among the early Christians we see the rite falling into disuse. Although the Founder of Christianity was circumcised St. Paul aiming for a cosmopolitan faith discouraged the practice. St. Augustine was of the position that it took away the original sin despite the other Fathers like Justus,Tertullian ,Ambrose et al stuck with Pauline stand. This practice continued in Ethiopia and for the descendents of Sheba it is a mark of Nobility. The Ethiopians follow the Jewish custom in performing the rite within 8 days after the birth and baptize boys after forty and girls after eight days. A circumcised man became a Jew after he was bled before three witnesses. This is called the ‘blood of alliance.’Similar practise was followed by Armenians and other Christians who were compelled to become Moslem in the bygone days and wished to return to Christianity.( from footnote supplied by Richard Burton in his 1001 Night.)

benny

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