A Short History of Nearly Everything: Chapter 28 Summary & Analysis

In 1887, young Dutch doctor Marie Eugène François Thomas Dubois is in Sumatra looking for the earliest human remains on Earth on a “hunch,” because he thinks that Sumatra is full of caves and that ancient humans lived in caves. Almost miraculously, he finds what he’s looking for. At the time, early human fossil records consist of only five incomplete Neanderthal skeletons. Even these are met with resistance: one anthropologist suggests the Neanderthal’s heavy brow ridge is caused by excessive frowning and that the skeleton is much more recent.

Dubois’s team find part of a skull that they think is the missing link between apes and humans. It’s popularized as “Java Man.” To Dubois’s surprise, he’s met with hostility from the scientific community upon his return to Europe, most of whom argue that the skull belongs to a gibbon. In 1924, anatomist Raymond Dart receives a complete child’s skull that looks like it might be the missing link, and he dubs it “southern ape man of Africa.” His claim, too, is met with hostility by the scientific community. Efforts multiply, and by the 1950s, there are so many disagreements about how to interpret skeletons that that some scientists argue for 100 different species of hominid.    

F. Clark Howell’s efforts to simplify the classification into two categories are largely rebuffed in the 1960s. Today, the picture is still in disarray. Bryson says some scientists think there are only two types of hominoid, others think there are 20, and very few agree on which ones are the right ones. Bryson says that part of the problem is lack of evidence. Scientists have to speculate about entire species based on a mere 5,000 partial skeletons from scattered ages in history—collectively, they’d fit in the back of a pick-up truck with room left over. The patchiness of the record is what makes each skull seem like radically different to the others, and it triggers many disputes.

With all that mind, Bryson tentatively argues that for 99.99999 percent of our history, chimpanzees and humans were in the same ancestral line. Seven million years ago, the “australopithecines” (of many shapes and sizes) emerged from Africa’s tropical forests and began roaming the savanna, becoming the dominant hominid species for five million years. The most famous specimen from this time is named Lucy: she’s 3 feet tall, and she can walk as well as climb. In 2001 and 2002, additional bipedal specimens were found.

Bipedalism is a risky evolutionary move—it demands completely reworking the pelvis and making the birth canal much narrower. This means that babies have to pass through with smaller brains, and they demand longer infant care post-birth. This is even harder for Lucy and her contemporaries, who have orange-sized brains. Bryson speculates that Lucy and her clan came down from the trees because they had to. Changing tectonic plate activity made forests sparser in Africa. Of the six or so hominid types living in Africa around 2 million years ago, only one survived: “Homo.” Conventionally, “Homo habilis” (the first and most primitive species) comes first, and “Homo sapiens” (meaning us) comes last—but there’s a disputed number of species in between, including “Homo erectus.”

Scientists have no idea why the Homo brain suddenly started growing 2 million years ago. Ian Tattersall thinks it might be an evolutionary accident. Nobody knows why the other hominoids disappeared, though Matt Ridley suggests that humans ate them. Tattersall says it’s hard for humans to accept that our existence is just an accident and that there’s nothing “inevitable” about it, but that may well be the case. Homo erectus is considered the dividing line between humans and apes. Scientist Alan Walker describes Homo erectus as a fearsome creature: “the velociraptor of its day.”

Richard Leakey discovers the first near-complete Homo erectus skeleton in the 1980s, of a nine- to 12-year-old boy who died 1.54 million years ago. Leakey believes that Homo erectus skulls show evidence of a capacity for speech (which chimps lack), though Walker disagrees. The spread of Homo erectus around the globe is so fast that some scientists think another hominid genus might have spontaneously arisen in Asia. Bryson says that all scientists do know is that about a million years ago, bipedal beings left Africa and spread around the globe. Everything else remains a matter of speculation.