Indonesian fossils extend evolutionary timeline but create new problems.
It’s been 12 years since researchers found a skull and some bones of diminutive people in Liang Bua Cave on the island of Flores, Indonesia (10/27/04). Evidence indicated the creatures used tools and walked upright, but their small stature, about 1 meter in height, startled everyone. The finds were assigned to a new genus of Homo, H. floresiensis, and declared to be descendants of Homo erectus that had migrated onto the island and shrunk in size due to “island dwarfism.” A big problem was that the fragments were initially dated at just 18,000 years old, far too young for human ancestors. Later efforts moved the date back to 60,000 years, but the discovery prompted a decade of efforts to fit these bones into an evolutionary scenario.
Now there are new bones. When Nature released a paper this week about new fragments of bone found in the area, and provided another Nature paper about the date and context of the bones (re-dated at 700,000 years), the media flew into action:
- How the Homo floresiensis kept their tools as they shrank into island life (PhysOrg)
- Likely hobbit ancestors lived 600,000 years earlier (Science Magazine)
- New Fossils Hint ‘Hobbit’ Humans Are Older Than Thought (National Geographic)
- Hobbit find shows tiny humans shrank ‘rapidly’ (Pallab Ghosh at the BBC News)
- Mystery human hobbits ruled tiny Asian island 700,000 years ago (New Scientist)
- Miniature ‘Hobbit’ Humans Had Even Smaller Ancestors (Charles Q. Choi at Live Science)
Most of the media reports led with artwork portraying a wide-eyed, dark-skinned, black-haired face with flared nostrils. Obviously, skin color, hair color and nose tissue is not preserved from any of the fossils, so it is unclear why they are pictured that way.
The new bones, found 74 kilometers away from Liang Bua, consist of a few teeth (a molar and two canines) and fragment of a jaw, possibly from one adult and one or more juveniles. Years earlier, hundreds of stone tools indicating a non-trivial amount of cognitive skill, had been found on the nearby island of Sulawesi. The new emerging story, being repeated by all the media, is that human ancestors (possibly Homo erectus) moved into the area a million years ago and shrank rapidly, in just 300,000 years. Then they lived among “miniature elephants, giant rats and Komodo dragons” for hundreds of thousands of years in their hobbit-size forms, says Mark Moore, a co-author of the lead paper, at The Conversation. However, the new story adds new questions while supplying fragmentary new data:
Analysis of these new fossils supports the hypothesis that Homo floresiensis evolved from a population of large-bodied Homo erectus that were stranded on the island and subjected to the “island rule”. This is where selective pressures unique to islands cause large-bodied animal species to become smaller over time.
Surprisingly, we now have evidence that the founding population of Homo erectus shrunk to Hobbit size and evolved into the new species, Homo floresiensis, within 300,000 years of arriving there.
This is a dramatically short period in evolutionary terms. Yet this hominin used tools they made to adapt to the Flores environment, which in turn raises interesting questions about the technological niche characteristic of the genus Homo.
Moore describes how difficult making stone tools is. He tells about his own experience trying the skill. “But, despite what you might assume, controlling the process is not easy,” he says. “It requires complex mental evaluations of geometrical configurations on the stone, and blows that are simultaneously controlled and forceful.” It’s more than simple banging rocks together, like some monkeys are observed to use for cracking open shellfish and nuts (loosely described by New Scientist as “Stone Age culture”).
According to the new scenario, proposed by lead author Gerrit van den Bergh, the hobbits became “stranded” on Flores and evolved there for the next 700,000 years. How did they arrive? Science Magazine suggests that they were “perhaps washed in by tsunamis from the islands of Java or Sulawesi.” Is that plausible? Sulawesi is at least 180 miles by sea from Flores. Getting to Flores from Java (360 miles away) would require at least three hops of ten to 25 miles over open water. Besides, both Java and Sulawesi are islands themselves, so how did the people get there? Yet if they navigated to Flores purposefully on some kind of watercraft, it becomes hard to believe they remained stuck on an island of “meagre resources” for 700,000 years, where the only way to survive was to evolve small size. Why didn’t they build boats to find a better place? The story also requires Homo erectus to show up in Indonesia 1.5 million years ago—twice the entire length of time H. floresiensis supposedly lived on Flores. Over such a long time, why didn’t the big boys on the mainland build a ship to come rescue the hobbits? It’s a tale more fanciful than Middle Earth.
Not everyone is buying the story. Ewen Callaway writes for Nature,
Both Fred Spoor, a palaeontologist at University College London, and palaeoanthropologist Chris Stringer at London’s Natural History Museum agree that H. erectus is now the best fit for the hobbit’s ancestor, although Stringer isn’t so sure that the shrinkage happened on Flores. It’s just as likely that the hobbit emerged on another island, such as Sulawesi, and then moved to Flores, he says.
But William Jungers, a palaeoanthropologist at Stony Brook University in New York, says that the fossils are not complete enough to favour the H. erectus origin: “I don’t believe these scrappy new dental specimens inform the competing hypotheses for the origin of the species one way or another.”
People don’t just “emerge” on islands. Stringer needs to explain how the ancestors got to Sulawesi, which is 74 to 163 miles away from the Indonesian mainland. Did a tsunami wash them there, too, without drowning them all? Or were the ancestors smart enough to migrate by intelligent design? Aida Gómez-Robles, writing for Nature, ignores that question. So do the Editors of Nature.
Everyone agrees that more digging will be required. Elizabeth Culotta ends her coverage in Science by remarking, “the fragmentary nature of the fossils leaves parts of the story open to interpretation.” In that regard, little has changed since 2004.
People “emerging” on islands; people doing nothing but banging rocks for hundreds of thousands of years; people evolving rapidly then evolving slowly; finely-tuned tsunamis carrying people to an island without drowning them; people shrinking on the same island where lizards and rats grow giant-sized; oh, what a tangled web they weave when they first begin to Darwinize.
Black people should be incensed at the artwork. They should claim that the stupidity of the hobbits to get off their island prison was because of their whiteness. If it were blacks that got stranded on Flores while surfing tsunamis, they would have had the sense to call the Java Man ferry service for a ride back to the mainland.