The Scientific Journals

By : Ian Tattersall

ALTHOUGH THIS is all true, H. sapiens embodies something that is undeniably unusual and is neatly captured by the fact that we are alone in the world today. Whatever that something is, it is related to how we interact with the external world: it is behavioral, which means that we have to look to our archaeological
record to find evidence of it. This record begins some 2.5 million years ago with the production of the first
recognizable stone tools: simple sharp flakes chipped from parent “cores.” We don’t know exactly who the inventor was, but chances are that he or she was something we might call an australopith.

This landmark innovation represented a major cognitive leap and had profound long-term consequences for hominids. It also inaugurated a pattern of highly intermittent technological change.
It was a full million years before the next significant technological innovation came along: the creation about 1.5 million years ago, probably by H. ergaster, of the hand ax. These symmetrical implements,
shaped from large stone cores, were the first tools to conform to a “mental template” that existed in the toolmaker’s mind. This template remained essentially unchanged for another million years or more, until the invention of “prepared-core” tools by H. heidelbergensis or a relative. Here a stone core was elaborately shaped in such a way that a single blow would detach what was an effectively finished implement.

Among the most accomplished practitioners of prepared-core technology were the large-brained, big-faced and low-skulled Neandertals, who occupied Europe and western Asia until about 30,000 years ago. Because they left an excellent record of themselves and were abruptly replaced by modern humans who did the same, the Neandertals furnish us with a particularly instructive yardstick by which to judge our own uniqueness. The stoneworking skills of the Neandertals were impressive, if somewhat stereotyped, but they rarely if
ever made tools from other preservable materials. And many archaeologists question the sophistication of their hunting skills.

Further, despite misleading early accounts of bizarre Neandertal “bear cults” and other rituals, no substantial
evidence has been found for symbolic behaviors among these hominids or for the production of symbolic objects—certainly not before contact had been made with modern humans. Even the occasional Neandertal practice of burying the dead may have been simply a way of discouraging hyenas from making incursions
into their living spaces or have a similar mundane explanation. This view arises because Neandertal burials
lack the “grave goods” that would attest to ritual and belief in an afterlife. The Neandertals, in other words, though admirable in many ways and for a long time successful in the difficult circumstances of the late ice ages, lacked the spark of creativity that, in the end, distinguished H. sapiens.



Although the source of H. sapiens as a physical entity is obscure, most evidence points to an African origin perhaps between 150,000 and 200,000 years ago. Modern behavior patterns did not emerge until much later. The best evidence comes from Israel and its surrounding environs, where Neandertals lived about 200,000 years ago or perhaps even earlier. By about 100,000 years ago, they had been joined by anatomically modern H. sapiens, and the remarkable thing is that the tools and sites the two hominid species left behind are essentially identical. As far as can be told, these two hominids behaved in similar ways despite their anatomical differences. And as long as they did so, they somehow contrived to share the  Levantine environment.

The situation in Europe could hardly be more different. The earliest H. sapiens sites there date from only about 40,000 years ago, and just 10,000 or so years later the formerly ubiquitous Neandertals were gone.  Significantly, the H. sapiens who invaded Europe brought with them abundant evidence of a fully formed and unprecedented modern sensibility. Not only did they possess a new “Upper Paleolithic” stoneworking  technology based on the production of multiple long, thin blades from cylindrical cores, but they made tools from bone and antler, with an exquisite sensitivity to the properties of these materials.

Even more significant, they brought with them art, in the form of carvings, engravings and spectacular cave paintings; they kept records on bone and stone plaques; they made music on wind instruments; they crafted intricate personal adornments; they afforded some of their dead elaborate burials with grave goods (hinting at social stratification in addition to belief in an afterlife, for not all burials were equally fancy); and their living sites were highly organized, with evidence of sophisticated hunting and fishing. The pattern of intermittent
technological innovation was gone, replaced by constant refinement.  Clearly, these people were us.

Next : Competing Scenarios
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By : Ian Tattersall

FROM THE BEGINNING, almost from the very moment the earliest hominid biped—the first “australopith”—made its initial hesitant steps away from the forest depths, we have evidence for hominid
diversity. The oldest-known potential hominid is Sahelanthropus tchadensis, represented by a cranium from the central-western country of Chad [see illustration on page 26]. Better known is Australopithecus anamensis, from sites in northern Kenya that are about 4.2 million years old.

A. anamensis looks reassuringly similar to the 3.8- to 3.0-million-year-old Australopithecus afarensis, a smallbrained, big-faced bipedal species to which the famous “Lucy” belonged. Many remnants of A. afarensis have been found in various eastern African sites, but some researchers have suggested that the mass of fossils described as A. afarensis may contain more than one species, and it is only a matter of time until the subject is raised again. In any event, A. afarensis was not alone in Africa. A distinctive jaw, from an australopith
named A. bahrelghazali, was found in 1995 in Chad. It is probably between 3.5 and 3.0 million years old
and is thus roughly coeval with Lucy, as is the recently named new form Kenyanthropus platyops.

In southern Africa, scientists reported evidence in 1999 of another primitive bipedal hominid species. As yet unnamed and undescribed, this distinctive form is 3.3 million years old. At about three million years ago, the same region begins to yield fossils of A. africanus, the first australopith to be discovered (in 1924). This species may have persisted until not much more than two million years ago. A 2.5-million-year-old species
from Ethiopia, named Australopithecus garhi in 1999, is claimed to fall in an intermediate position between A. afarensis, on the one hand, and a larger group that includes more recent australopiths and Homo, on the other. Almost exactly the same age is the first representative of the “robust” group of australopiths,
Paranthropus aethiopicus. This early form is best known from the 2.5-million- year-old “Black Skull” of northern Kenya, and in the period between about 2 and 1.4 million years ago the robusts were represented all over eastern Africa by the familiar P. boisei. In South Africa, during the period around 1.6 million
years ago, the robusts included the distinctive P. robustus and possibly a closely related second species, P. crassidens.

I apologize for inflicting this long list of names on readers, but in fact it actually underestimates the number of australopith species that existed. What is more, scientists don’t know how long each of these creatures lasted. Nevertheless, even if average species longevity was only a few hundred thousand years, it is clear that from the very beginning the continent of Africa was at least periodically—and most likely continually— host to multiple kinds of hominids.

The appearance of the genus Homo did nothing to perturb this pattern. The 2.5- to 1.8-million-year-old fossils from eastern and southern Africa that announce the earliest appearance of Homo are an oddly assorted lot and probably a lot more diverse than their conventional assignment to the two species H. habilis and H. rudolfensis indicates. Still, at Kenya’s East Turkana, in the period between 1.9 and 1.8 million years ago, these two species were joined not only by the ubiquitous P. boisei but by H. ergaster, the first hominid of essentially modern body form. Here, then, is evidence for four hominid species sharing not just the same continent but the same landscape [see illustration on opposite page and below].

The first exodus of hominids from Africa, presumably in the form of H. ergaster or a close relative, opened a vast prospect for further diversification. One could wish for a better record of this movement, and particularly of its dating, but there are indications that hominids of some kind had reached China and Java by about 1.8 million years ago. A lower jaw that may be about the same age from Dmanisi in ex-Soviet Georgia
is different from anything else yet found [see “Out of Africa Again ... and Again?” by Ian Tattersall, on page 38]. By the million-year mark H. erectus was established in both Java and China, and it is possible that a more robust hominid species was present in Java as well. At the other end of the Eurasian continent, the
oldest-known European hominid fragments— from about 800,000 years ago— are highly distinctive and have been dubbed H. antecessor by their Spanish discoverers.

About 600,000 years ago, in Africa, we begin to pick up evidence for H. heidelbergensis, a species also seen at sites in Europe—and possibly China—between 500,000 to 200,000 years ago. As we learn more about H. heidelbergensis, we are likely to find that more than one species is actually represented in this group of fossils. In Europe, H. heidelbergensis or a relative gave rise to an endemic group of hominids whose bestknown representative was H. neanderthalensis, a European and western Asian species that flourished between about 200,000 and 30,000 years ago. The sparse record from Africa suggests that at this time independent develop-including the emergence of H. sapiens. And in Java, possible H. erectus fossils
from Ngandong were dated to around 40,000 years ago, implying that this area had its own indigenous hominid evolutionary history for perhaps millions of years as well.

The picture of hominid evolution just sketched is a far cry from the “Australopithecus africanus begat Homo erectus begat Homo sapiens” scenario that prevailed 40 years ago—and it is, of course, based to a great extent on fossils that have been discovered since that time. Yet the dead hand of linear thinking still lies heavily on paleoanthropology, and even today quite a few of my colleagues would argue that this scenario overestimates diversity. There are various ways of simplifying the picture, most of them involving the cop-out of stuffing all variants of Homo of the past half a million or even two million years into the species
H. sapiens.

My own view, in contrast, is that the 20 or so hominid species invoked (if not named) above represent a minimum estimate. Not only is the human fossil record as we know it full of largely unacknowledged morphological indications of diversity, but it would be rash to claim that every hominid species that ever existed is represented in one fossil collection or another. And even if only the latter is true, it is still clear that the story of human evolution has not been one of a lone hero’s linear struggle.

Instead it has been the story of nature’s tinkering: of repeated evolutionary experiments. Our biological history
has been one of sporadic events rather than gradual accretions. Over the past five million years, new hominid species have regularly emerged, competed, coexisted, colonized new environments and succeeded—or failed. We have only the dimmest of perceptions of how this dramatic history of innovation and interaction
unfolded, but it is already evident that our species, far from being the pinnacle of the hominid evolutionary
tree, is simply one more of its many terminal twigs.

Next : The Roots of Our Solitude
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By : Ian Tattersall

Homo sapiens has had the earth to itself for the past 25,000 years or so, free and clear of competition from other members of the hominid family. This period has evidently been long enough for us to
have developed a profound feeling that being alone in the world is an entirely natural and appropriate state of affairs.

So natural and appropriate, indeed, that during the 1950s and 1960s a school of thought emerged that claimed, in essence, that only one species of hominid could have existed at a time because there was simply no ecological space on the planet for more than one culturebearing species. The “single-species hypothesis”
was never very convincing even in terms of the rather sparse hominid fossil record of 40 years ago. But the
implicit scenario of the slow, singleminded transformation of the bent and benighted ancestral hominid into the
graceful and gifted modern H. sapiens proved powerfully seductive—as fables of frogs becoming princes always are.

So seductive that it was only in the late 1970s, following the discovery of incontrovertible fossil evidence that hominid species coexisted some 1.8 million that the single-species hypothesis was abandoned. Yet even then, paleoanthropologists continued to cleave to a rather minimalist interpretation of the fossil record. Their  tendency was to downplay the number of species and to group together distinctively different fossils under
single, uninformative epithets such as “archaic Homo sapiens.” As a result, they tended to lose sight of the fact that many kinds of hominids had regularly contrived to coexist.

Although the minimalist tendency persists, recent discoveries and fossil reappraisals make clear that the biological history of hominids resembles that  of most other successful animal families. It is marked by diversity rather than by linear progression. Despite this rich history— during which hominid species developed
and lived together and competed and rose and fell—H. sapiens ultimately emerged as the sole hominid. The
reasons for this are generally unknowable, but different interactions between the last coexisting hominids—H. sapiens and H. neanderthalensis—in two distinct geographical regions offer some intriguing insights.

Next : A Suites of Species
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It’s quite a tale. Perhaps five million to 10 million years ago, a primate species diverged from the chimpanzee line. This was the forerunner of humanity and a host of other beings who were almost but not quite human. For a time, a throng of hominid species shared the planet; at least four even coexisted in the same region. By around four million years ago, our progenitors and others had mastered the art of walking upright. Some two million years later they strode out of Africa and colonized entirely new lands. Certain groups learned to make sophisticated tools and, later, artwork and musical instruments. The various species clashed, inevitably. Modern humans, who entered Europe 40,000 years ago, may have slaughtered Neandertals (when they weren’t interbreeding with them).  Eventually only one species, Homo sapiens, was left. We thus find ourselves alone and yet the most numerous and successful primates in history.

Reading the cracked brown fragments of fossils and sequences of DNA, however, scientists have found clues that the story of human origins has more convolutions. The account of our shared human heritage now includes more controversial plot twists and mysteries. Was the remarkable seven-million-year-old skull found
in July 2002 in Chad really one of our first forebears, or a distant dead-end cousin with precociously
evolved features? Did modern humans really originate in Africa alone, as is widely held, or in multiple locales?