Faithful Ancestors

A weird kind of creature strode across the eastern African landscape from around 4 million to 3 million years ago. Known today by the scientific label Australopithecus afarensis, these ancient ancestors of people may have taken the battle of the sexes in a strange direction, for primates at any rate. True, no one can re-create with certainty the court and spark that led to sexual unions between early hominids. Nothing short of a time machine full of scientifically trained paparazzi could manage that trick.

All is not lost, though. Scientists are looking to fossil remains of A. afarensis to provide, as a prehistoric tabloid would, a revealing exposé of the hominid's intimate tendencies. A statistical analysis 2 years ago indicated that A. afarensis males exhibited only a moderate size advantage over females, rather than the larger difference seen in gorillas. According to Owen Lovejoy and Philip L. Reno, both of Kent (Ohio) State University, who directed that study, the size similarity implies that A. afarensis adults of both sexes favored long-term relationships, which arose as a matter of survival, not morality. Sleeping around just didn't cut it during hominids' start-up era.

That view has generated controversy, which comes as no surprise to the Kent State scientists. They themselves had unabashedly dismissed other researchers' earlier work that depicted A. afarensis males as the considerably larger sex, with the fiercest male fighters monopolizing the mating game.

However, some recent work provides evidence for A. afarensis sex differences that were considerably greater than those in modern people and that approach those in gorillas, according to J. Michael Plavcan of the University of Arkansas in Fayetteville and his colleagues. They report their analysis in the March Journal of Human Evolution. Large sex differences would indicate a mating style similar to that of modern gorillas.

Lovejoy and Reno, however, stand by their earlier conclusions. "It's entirely possible that much of our sexual physiology and anatomy had already evolved in australopithecines," Lovejoy says. "That set the stage for massive brain growth in our later fossil ancestors."

Anthropologists discovered evidence of A. afarensis, including the partial skeleton dubbed Lucy, in eastern Africa more than 30 years ago. The bones seemed to fall into two size categories. At that time, researchers butted heads over whether these bones represented two species of human ancestors that lived at the same time or one species that included males with big, bulky bodies relative to those of females.

After noting similar shapes of the larger and smaller remains, proponents of the one-species view won out. Using measurements of people's bones in relation to body weight as a reference, investigators then estimated that A. afarensis males weighed an average of 98 pounds, while their female counterparts tipped the scales at only 65 pounds. That's a much greater sex disparity in weight than is found in people today but approaches that measured among gorillas and orangutans.

Many researchers concluded that in Lucy's species, as among gorillas, the toughest males dominated the mating scene. Gorilla males tend to fight among themselves, baring daggerlike canine teeth. Winners do the lion's share of mating with available females, whom the dominant males guard from skulking suitors.

Demonstrating another lifestyle, chimps exhibit virtually no size differences between sexes, but males retain large, fanglike canines, Lovejoy notes. A female typically mates numerous times with several partners during periods of sexual receptivity, which she advertises via temporarily swollen breasts and hindquarters.

According to Lovejoy, though, behaviors of gorillas or chimps can't serve as a model for Lucy and her comrades. In 1981, he proposed that they were descendants of a new kind of primate built for what he calls social monogamy. A. afarensis males blended an upright stance and unusually small, nonthreatening canine teeth. And the female anatomy masked signs of ovulation through features such as permanently enlarged breasts, he says.

Given this species' million-year run of success, Lovejoy theorizes, its males probably obtained food consistently by forming working alliances, mainly among close relatives. Each successful provider thus upped his chances of being accepted as a female's sole mate, the best way to ensure that he would become a dad. From the female perspective, a steady mate would be a good bet not only to bring home food but also to assist in child care.

However, modest size differences between the sexes typically characterize mammals with a penchant for soul mates, rather than the gorillalike pattern that had been proposed.

Ten years after Lovejoy set forth the idea of social monogamy among australopithecines, evidence continued to pile up supporting a substantial size difference between males and females. In 1991, Henry M. McHenry of the University of California, Davis published estimates of large weight disparities.

Lovejoy countered that those calculations used as a reference point the sex differences observed in modern people, which he says probably don't correspond to those of 3-million-year-old hominids. He also pointed out that McHenry's analyses rested on a small number of fossils that covered a time span of at least 500,000 years and were unearthed at sites separated by nearly 500 miles. The specimens could have come from populations showing a variety of unique male-female anatomical contrasts.

Finally, cursed with a scarcity of pelvic remains that could clearly distinguish wider-hipped females from slimmer-hipped males, McHenry simply assumed that big bones came from males and small bones came from females, Lovejoy says.

In 2003, Lovejoy and his coworkers employed a novel statistical method to simulate skeletal-size differences between ancient sexes without trying to gauge their weights. The enterprise hinged on using measurements of Lucy's partial skeleton to estimate sizes of crucial but missing bones for a set of A. afarensis individuals known as the First Family. These fossils, which represent as many as 22 or as few as 5 individuals, were unearthed near the spot where Lucy was found and, like her, date to 3.2 million years ago.

The researchers first measured the width of Lucy's well-preserved femur head, the ball of the upper-leg bone that fits into the hip joint. They then determined the size of various other parts of Lucy's arm and leg bones relative to femur-head width. Lovejoy focused on femur-head size because it's considered a reliable indicator of overall body size.

Next, the scientists measured the First Family arm and leg fossils that corresponded to those for Lucy. Armed with Lucy's skeletal dimensions, the team calculated femur-head sizes. They tagged individuals with big femur heads as male and those with small femur heads as female. In further studies the researchers found that femur-head sizes accurately predict sex and overall body size in people, chimps, and gorillas.

Whether the First Family included two dozen or only a half-dozen members, males exhibited a moderate size advantage over females, close to that observed in people, Lovejoy's team found.

Moderate, humanlike size differences between A. afarensis males and females accompanied both an evolutionary shriveling of males' canine teeth and a shift of sexual physiology away from chimplike ancestors and toward humans, Lovejoy asserts. For instance, he suspects that that's when ovulation became concealed and males evolved physical accommodations to mate regularly rather than for short, intense periods during ovulation. The new-style males produce modest amounts of sperm continuously rather than larger amounts timed to ovulation, as do gorillas.

Australopithecines, as highly mobile creatures locked into a socially complex mating game, lit a fuse of brain expansion that exploded in ensuing Homo species, Lovejoy proposes. Ironically, large brains unleashed cultural evolution, resulting in a plethora of human sexual and mating practices that go far beyond anything Lucy could have imagined, he says.

The Kent State scientists' portrayal of A. afarensis sexes has received some positive reviews. Robert G. Tague, an anthropologist at Louisiana State University in Baton Rouge calls Lovejoy's method of estimating skeletal-size differences "a promising one" and suspects that Lucy's kind indeed preferred social monogamy.

Lovejoy's findings indicate that early hominids "may have been more humanlike [than apelike] in their basic social behavior," comments Clark S. Larsen, an anthropologist at Ohio State University in Columbus.

But other researchers contend that the accumulated evidence supports striking size differences between A. afarensis sexes. These scientists reject Lovejoy's unconventional approach. To begin with, says Plavcan, the First Family consists mainly of large-bodied males and thus fosters an underestimate of size differences.

Plavcan and his colleagues determined the relationship between various skeletal measures and body mass for 658 people from eight populations in different parts of the world. With those correlations, the team made new calculations of femur-head size and body mass for seven A. afarensis specimens not in the First Family and assigned sex on the basis of size.

This work reveals sex differences considerably greater than those in people and approaching those in gorillas, according to Plavcan's team.

Particularly fierce males in Lucy's species probably monopolized mating, although how they did so without sharp canines remains unclear, Plavcan says.

Mating-minded A. afarensis males, McHenry theorizes, literally took up arms. An upright posture freed their hands for punching, throwing rocks, and other mayhem. The best fighters thus defended their exclusive sexual access to adult females.

It's risky to judge a hominid's body weight by the size of its bones because nutrition and other factors influence the amount of muscle and fat, says Christopher Ruff of Johns Hopkins University School of Medicine in Baltimore. He discounts Lovejoy's conclusions, arguing that an individual's skeletal size often bears little relationship to body weight.

UC-Davis' McHenry is sticking with his earlier calculation that A. afarensis males were about 50 percent heavier than females. Humanlike size proportions for the sexes evolved much later, around 1.7 million years ago in Homo erectus, McHenry argues. Men today are about 15 percent heavier than women.

Other scientists express a mix of chagrin and disdain at the amount of energy that researchers have expended on trying to separate fossil boys from girls. Investigators need to drop their obsession with the sex of fossils and examine how individual differences in skeletal anatomy arise, contends Maciej Henneberg of the University of Adelaide in Australia. For body weight and many skull measurements, including braincase size and facial width, individuals within each sex usually differ far more from each other than average members of opposite sexes do, he argues.

Erik Trinkaus of Washington University in St. Louis also derides efforts to identify the sex of ancient bones. Sex assessments always begin with the unjustified assumption that bigger bones must belong to males and smaller ones to females, he says. And the numbers of individual specimens of A. afarensis and other ancient hominid species are too few to generate reliable estimates of male and female size ranges, in his opinion.

Louisiana State's Tague doesn't go that far, but he notes that even the pelvis, the body part regarded as the gold standard for telling apart primate sexes, is surprisingly tough to read. His work shows no consistent pattern of the pelvis being larger in females than in males.

The shape of Lucy's partially preserved pelvis leaves her sexual identity unclear, Tague notes. Her diminutive size led Tague and Lovejoy in a 1998 paper to peg Lucy as female.

Reports on new fossil finds of A. afarensis and even older hominid species are expected soon. Lovejoy plans to factor skeletal data from these discoveries into a larger examination of ancient sex differences.

From Lucy's era to our time, the battle of the sexes appears destined to rage on.

Isaiah 40:22 says, "It is he that sitteth upon the circle of the earth..." The Earth, though, is not a circle, it is an oblate spheroid.

True, that might be a problem if the original language had been modern English but Isaiah was written in ancient Hebrew. Strong defines the Hebrew word meaning circle, circuit or compass. You may disagree, but to me that sounds like a good approximation of oblate spheroid in an ancient language. I'm not sure how advanced the ancient Hebrews were in mathematics, but if the earth is a sphere and you head east on a constant latitude you will make a circuit or circle back where you started. If the earth is flat, you have no such circuit or circular path.

"I'm not sure how advanced the ancient Hebrews were in mathematics, but if the earth is a sphere and you head east on a constant latitude you will make a circuit or circle back where you started. If the earth is flat, you have no such circuit or circular path."

The first thing you should do before concluding that, is determine if ancient Hebrew had a word for ball or sphere or similar. If they do, then your interpretation is unlikely. If they didn't then your interpretation will carry more weight. As it is, it sounds like you're reaching.

He is saying that differences within groups is more statistically signifincant then variations among other groups.

Yeah, except for the variation he's suggesting, for all primates that have been so studied including humans, gorillas and chimps, it isn't true.

He is suggesting that the liklihood of a set of small bones being of the same sex as a set of larger bones are greater then the bones to be an average male and an average female.

If he were arguing that we don't have enough australopithicine and other pre-human bones to make a statistically valid case, he'd have an argument. The probablilities you describe depend on the relative location of the means of the two groups. And it is true that we are dealing in probabilities, not certainties, as always in statistics. But the argument he seems to be making is more of the "you can't rule it out beyond a reasonable doubt" variety, which plays well to reporters whose last science class was in grade school somewhere, but is specious as a scientific argument.

He is basically saying that you can't neccessarliy claim that smaller bones are a different sex by size along and you need other data.

But that is the biggest difference between the long bones of adult male and female in our species and all those that are closely related. (In humans, we also have differences in skull, jaw and pelvis, but these bones haven't survived well in the australopithicine fossil recor).

Science doesn't deal in certainties in the way that faith does. You follow the probabilities (and if you are honest, you join all the others in trying to prove yourself wrong and advance to the next idea).

d.o.l.

Criminal Number 18F

"I'm not sure how advanced the ancient Hebrews were in mathematics"

Not very advanced at all, unfortunately. They were behind the Egyptians and Babylonians who calculated Pi as 3 and a fraction. The Bible says...

1 Kings 7:23 He [Solomon] made the Sea of cast metal, circular in shape, measuring ten cubits from rim to rim [diameter = 10] and five cubits high. It took a line of thirty cubits to measure around it. [circumference = 30]

Showing that they thought Pi was 3, so the knowledge of the people who wrote the Bible was less advanced than their contemporaries and did not exhibit any divine knowledge or insight; just the incorrect mathematical musings of a man.

It seems to me that it is an approximation suitable for the audience at hand. A good rule for understanding the Bible is that it is not written to us but written for us. (Romans 15:4)I just take it that God did not see that a more precise approximation was needed.

And who's the infallible judge on how precise this approximation need be? As we know pi is a repeating decimal. The only perfect representation of pi would take an infinite number of decimal places. How many decimal places do you demand of God to meet your standard of preciseness? If the infinite God decided for this purpose that this, the correct approximation to an integer, was a close enough approximation, who are we to demand more? As Deuteronomy 6:16 states:

Ye shall not tempt the LORD your God

The law of the rebellious son was part of the penal code of Israel under the law of Moses. The Bible never applies this mankind as a whole. So if I were you, I wouldn't be worried about it being applied in our enlightened world today where juvenile delinquents terrorize their peers and society as a whole. And if you note the context of the verse, this isn't dealing with a little son who merely balks at eating his vegetables. There is a reference to the son as a drunkard. This appears to be like a hard version of the habitual criminal law that we in the West have. And you have to admit, this law was more effective than ours in eliminating a menace 2 society before he left a trail of mayhem and innocent blood.

I've not found a Hebrew word for sphere. But even if there is one, the figure in this verse might have been meant to refer to the circuit around the spherical earth. And an advanced Biblical knowledge of the nature of the globe is indicated by Job 26:7 where the earth is said to "hang on nothing".

True, that might be a problem if the original language had been modern English but Isaiah was written in ancient Hebrew. Strong defines the Hebrew word meaning circle, circuit or compass.

But the earth is neither a circle, circuit or compass. These are all two dimensional constructs, and they simply do not indicate a three-dementional object.

Further, in Isaiah, at Isiah 22:18, it states, "He will surely violently turn and toss thee like a ball into a large country: there shalt thou die, and there the chariots of thy glory shall be the shame of thy lord's house." So there was no reason for the author of Isaiah to use circle as an analogy for oblate spheroid, when there was a more apt analogy used in the same book, unless the author believed the earth was flat, or, at least, did not know that the earth was an oblate spheroid.

Further, other verses in the bible indicate a flat earth, or at least indicate a shape other than an oblate spheroid:

Job 38:13 speaks of the "ends" or "edges" of the earth. And oblate spheroid has neither.
Matthew 4:8 has the devil taking Jesus up "an exceeding high mountain" and showing him all the kingdoms of the world. This is impossible on an oblate spheroid, for no mountain, no matter how high, can be seen on the opposite side of the sphere.
Similarly, in Daniel 4:10-11, mention is make of a tree so tall that it could be seen to the end of the earth. Such a thing is, again, impossible on an oblate spheroid. (Although this was spoken as in a dream, so, strictly speaking, it was not an assertion of the nature of things.)

You may disagree, but to me that sounds like a good approximation of oblate spheroid in an ancient language.

I disagree. It sounds nothing like an oblate spheroid. Using the word for "ball", as in Isiah 22:18, would be a good approximation, but not the word for "circle." Taking the bible literally, it means a circle, not an oblate spheroid. Unless you don't think the bible should be read literally.

I'm not sure how advanced the ancient Hebrews were in mathematics, but if the earth is a sphere and you head east on a constant latitude you will make a circuit or circle back where you started. If the earth is flat, you have no such circuit or circular path.

Not true. If you have a flat earth, and walk a path that has a fixed curve, you will make a circle back to where you started.

Job 38:13 speaks of the "ends" or "edges" of the earth. And oblate spheroid has neither. Matthew 4:8 has the devil taking Jesus up "an exceeding high mountain" and showing him all the kingdoms of the world. This is impossible on an oblate spheroid, for no mountain, no matter how high, can be seen on the opposite side of the sphere. Similarly, in Daniel 4:10-11, mention is make of a tree so tall that it could be seen to the end of the earth. Such a thing is, again, impossible on an oblate spheroid. (Although this was spoken as in a dream, so, strictly speaking, it was not an assertion of the nature of things.)

Job is a highly poetic book. To complain of such a figure of speech in a poetic book when today we hear the term "the four corners of the earth" is really reaching. Do you suppose anybody today who speaks of traveling the four corners of the earth really believes the earth is flat?

You are right about the dream in Daniel. It was a figurative description of a vision. And as far as the vision with Christ and the mountain, I think that just about everyone has understood that there was a vision involved. For one thing,if you go up to Mt Carmel, the highest mountain in the region, in that day you were not going to see anything but various Roman provinces of Palestine and Syria. But I don't see what the problem is. An account of a vision on a mountain is a long way from saying the earth is flat.

And no matter what the disagreement on what the Hebrew word in Isaiah 40:22 exactly means, it seems pretty clear that it does not say that the world is flat.

Accuracy to an integer would be 31. Saying it is 30 is a pretty large error for one whose eye is on the sparrow and can count the number of hairs on your head.

There's a difference between error and imprecision. To be more precise in your language you should have said. "Saying it is 30 is pretty imprecise for one whose eye is on the sparrow and can count the number of hairs on head."

If God is too imprecise for you here, I think that is between you and God. As for me, the very fact that God choose not to be more precise here is telling me that in this particular case, preciseness beyond the approximation is not needed.

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