When did humans start wearing clothes?
— Photo: K.K. Mustafah
Parasite: Head lice live in the hair and scalp and breed there.
One of the more endearing sculptures at the Mahabalipuram seashore temple site off Chennai is that of an elderly monkey picking out lice from the head of a younger one. Next time you see a human mother or sister de-lousing the hair of a youngster, you know where the practice comes from. Even the method is identical, except we use oil and comb.
Jumping species
We have also come to know now that lice came to colonize us humans from domesticated and other animals that lived in close proximity with us. The parasite ‘jumped’ species over to humans at least 100,000 years ago. DNA analysis by Dr. David Reed and associates of the University of Florida, published recently (J. Infect. Dis. 2008 Feb:197, 535, and J. Parasitol. 2008 May 16; 1 Epub), suggests that lice accompanied humans on their first migration out of Africa 100,000 years ago.
They did genetic analysis of the lice found on the heads of two 1,000-year-old mummies in Peru. Each of them had over 400 lice in their elaborately braided hair. Further, the DNA sequences of these varied very little from that of those seen today, and of those found in the heads of apes.
Lice that parasitize humans come in at least three types. The ones that prefer to stay in and colonize our head hair are termed, naturally, head lice.
The ones that prefer to colonize our body are called body lice. The third type prefers our genital or pubic region. Regardless of where they prefer to stay and breed, they live by sucking our blood.
Genetic analysis has shown that there are three genetically distinct strains or ‘clades’ of lice, termed A, B and C. Each clade is a distinct taxonomic group comprising a single ancestor and all the descendants of that ancestor.
The ones found on the heads of the Peruvian mummies are clade A. Clade B is seen more common in North America and Europe, while clade C is relatively rare. (We need to check which ones of these colonize us in India; here is a summer project for some student).
This distinction suggests that A was distributed across the Americas centuries before the first Europeans got there (about 600 years ago). Incidentally, clade A includes both head lice and body lice.
Body lice
Professor Mark Stoneking of the Max Planck Institute, Leipzig, Germany, has exploited the differences in the breeding habits of the head and body lice to advantage. While head lice live in the hair and scalp and breed there, body lice feed on the hairless parts of the body; but when it comes to breeding and living, they lay their eggs and live on clothing.
This little difference has enabled Stoneking and his associates to explore the question of when we humans began to clothe ourselves.
As they argue in their paper (Current Biology, 2003; 13: 1414-17), ‘this ecological differentiation probably arose when humans adopted frequent use of clothing, an important event in human evolution for which there is no direct anthropological evidence. We therefore used a molecular clock approach to date the origin of body lice, assuming that this should correspond with the frequent use of clothing’.
The group compared the DNA sequences of head and body lice of humans with those of lice colonizing the chimpanzee. They used the molecular clock method, which is a dating method based on the rate that specific types of mutation accumulate in the DNA sequence (particularly of the cell’s mitochondrion).
The divergence
This led them to first conclude that the divergence time of 5.5 million years between chimpanzees and humans also corresponds to the divergence time of human lice and chimpanzee lice.
Next, they compared the DNA sequences of human lice isolated in Africa with those of non-African ones. The African human lice showed greater diversity in their DNA than the non-African ones. This suggests that human lice originated in Africa. Incidentally, David Reed’s recent work (cited above) fits well with this, and underscores the idea of human migration out of Africa about 100,000 years ago.
The confirmation
Then, they compared the DNA variations between head lice and body lice of humans. Using the molecular clock data, they came to the conclusion that body lice originated no earlier than 42000 to 72000 years before present. This date of origin would imply that clothing by humans too would have started around this time.
Interestingly, this fits well with some, if meagre, archaeological data. While fur and fabrics do not fossilize, tools needed to make clothing, such as needles, do. Archaeologists have found needles in the Solutrean culture, which existed in France, about 40,000 years ago.
This was also the time when humans co-existed with their cousins, the Neanderthals. By now, we have a lot of reliable information about Neanderthal DNA, anatomy and physiology, social (and even spiritual) life.
It appears that they might have at best gone around wearing crude fur robes, if not naked (see the October issue of National Geographic Magazine).
There has been, as of today, no evidence of sewing tools from Neanderthal sites.
Clothing would thus seem to be an invention of homo sapiens, that too a recent one. Ironic that a blood-sucking parasite gives us a clue on when we started haute couture.
D. BALASUBRAMANIAN
dbala@lvpei.org
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