Feeds

Opposable thumbs for FISTS, not finesse, say bioboffins

Hands evolved to fight for sex, not to play Paganini

Boost IT visibility and business value

A pair of researchers at the University of Utah have published a paper arguing that our hands did not evolve merely so that our ancestors could perform delicate tasks, but also so that the males of the species could knock the crap out of one another in competition for mates.

"There are people who do not like this idea, but it is clear that compared with other mammals, great apes are a relatively aggressive group, with lots of fighting and violence, and that includes us," the paper's lead author, biology professor David Carrier told Science Daily. "We're the poster children for violence."

As Carrier and coauthor Michael Morgan write in "Protective buttressing of the human fist and the evolution of hominin hands", published in The Journal of Experimental Biology, "We propose that the derived proportions of hominin hands reflect, in part, sexual selection to improve fighting performance."

Compared with chimpanzees, we humans have stronger thumbs and shorter fingers and palms, which enables us to clench our fists and strengthen the resulting structure by folding our thumbs. Chimp fingers, on the other hand – no pun intended – form an open doughnut shape when curled, Carrier explained when announcing his research.

That research was sparked when he and fellow biomechanic Frank Fish discussed a paper Carrier had published which argued that whales could use their spermaceti organs as battering rams. "Frank didn't buy the argument," Carrier recalls, "and at one point he raised his fist and said, 'I can hit you in the face with this, but that is not what it evolved for'."

Open hands of chimpanzee and human

The structure of a chimpanzee's hand (left) is less well-adapted for punching than is man's (right)
(source: The Journal of Experimental Biology)

Carrier thought that Fish might be wrong, and decided to explore the offensive powers of the human hand. He and Morgan gathered a number of test punchers and slappers – "Fortunately, Michael had a lot of experience with martial arts and he knew people who were willing to serve as subjects," Carrier says – and had them deliver six types of blows, as hard as they could, to a punching bag that could measure the force of their strikes.

Surprisingly to Carrier and Morgan, all six types of aggression – overhead hammer fists and slaps, side punches and slaps, and forward punches and palm shoves – registered the same total amount of force. However, due to the fact that a straight-on punch concentrates that force into a smaller area, the amount of oomph delivered at the impact point with a clenched fist was 1.7 to three times greater than that of a slap.

"Because you have higher pressure when hitting with a fist, you are more likely to cause injury," Carrier says.

Carrier and Morgan then measured the ability of their subjects' clenched – or, as they say, "buttressed" – fist versus that of their hands with the fingers merely bent, not pressed aginst their palms and strengthened by that all-important thumb folded across them.

These tests showed that buttressing the fist resulted in a four-fold stiffening of the knuckle joint and a doubling of the ability of the fingers to transmit force, mainly due to the thumb helping hold them in place.

"Because the experiments show the proportions of the human hand provide a performance advantage when striking with a fist," Carrier says, "we suggest that the proportions of our hands resulted, in part, from selection to improve fighting performance."

Human fist before and after a punch

A pre-punch fist (grey) compresses only slightly (black) post-punch, with force being transmitted to the wrist
(source: The Journal of Experimental Biology)

Current evolutionary thinking, Carrier explains, is that when our ancestors dropped out of their arboreal homes and started walking upright on the ground, the hand evolved in order to better manipulate objects and to create and use tools.

"An alternative possible explanation," he says, "is that we stood up on two legs and evolved these hand proportions to beat each other."

And why did we want to beat each other? "Because the mating systems of great apes, including humans, are characterized by male–male competition, which can subject males to intense sexual selection on fighting performance," Carrier and Morgan write, "it is appropriate to question the role that this selection may have had on the evolution of the human hand." ®

Bootnote

Carrier's interest in punching and mating did not begin with his argument with Frank Fish. In May 2011 he published a paper describing research that compared the delivery of blows while hunched over on all fours to those delivered while standing, with results that he said "are consistent with the hypothesis that our ancestors adopted bipedal posture so that males would be better at beating and killing each other when competing for females."

Not only that, he said. "It also provides a functional explanation for why women find tall men attractive."

Gartner critical capabilities for enterprise endpoint backup

More from The Register

next story
LOHAN packs bags for SPACEPORT AMERICA!
Spanish launch goes titsup, we're off to the US of A
Gigantic toothless 'DRAGONS' dominated Earth's early skies
Gummy pterosaurs outlived toothy competitors
'Leccy racer whacks petrols in Oz race
ELMOFO rakes in two wins in sanctioned race
TRANSMUTATION claims US LENR company
Ten points of stuff out of a five pound bag
Boffins ID freakish spine-smothered prehistoric critter: The CLAW gave it away
Bizarre-looking creature actually related to velvet worms
CRR-CRRRK, beep, beep: Mars space truck backs out of slippery sand trap
Curiosity finds new drilling target after course correction
BAT-GOBBLING urban SPIDER QUEENS swell to ENORMOUS SIZE
But they'd lose a deathmatch against the coming Humvee-sized, armoured Arctic ones
Astronomers scramble for obs on new comet
Amateur gets fifth confirmed discovery
Boffins build CYBORG-MOTHRA but not for evil: For search & rescue
This tiny bio-bot will chew through your clothes then save your life
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
7 Elements of Radically Simple OS Migration
Avoid the typical headaches of OS migration during your next project by learning about 7 elements of radically simple OS migration.
BYOD's dark side: Data protection
An endpoint data protection solution that adds value to the user and the organization so it can protect itself from data loss as well as leverage corporate data.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?