Erectines
The term "Erectine" refers to one or more species (see below) of early members of our own genus, Homo. These species are well represented through thousands of fossils. The earliest fossils date from around 1.8mya. The most recent are more controversial. While Erectines had probably gone extinct from most of Europe and Africa by 500kya, they may have lived on in East or Southeast Asia until much more recently.
Erectines are the first members of our lineage to be recognizably human. An Australopith or a Habiline dressed up in a suit and walking down Main Street would generate a lot of stares. ("Why is there an ape walking down Main Street in a suit?") But an Erectine walking down Main Street would merely look like an odd person. ("OMG, Becky, look at her occipital bun!"). The Erectines evolved in the context of rapidly changing environments. This was the Pleistocene, the "Ice Age", but that name is misleading. The climate wasn't merely cold, it was extremely variable. That variability made flexible behavior advantageous, and led to the evolution of the large Homo brain.
Characteristics of Erectines:
Increased brain size, from 630cc to 900 cc. This is smaller, on average, than a modern human's brain, but there is overlap between the larger Erectine brains and smaller modern human brains.
Decreased tooth size. Dentition is smaller than any earlier hominin, reflecting a much softer diet. This is the result of cooking food using fire.
Human-like face, including jutting nasal bones to create an external nose, rather than a flat ape nose. This is an environmental adaptation to avoid the loss of moisture in hot, dry, open, or cold environments.
Human-like body. From the neck down, Erectines are virtually identical to modern people.
Erectines are much larger than earlier species, making them modern in size.
Waist from reduced gut volume, which reflects their higher-quality high-meat diet.
Modern limb proportions. Longer legs and shorter arms made it hard for them to climb trees, just like us.
Fully modern pelvis
Since many of the changes above are related to long-distance running, this is also the time when our ancestors probably developed hairlessness, sweating, and endorphin highs from exercise.
Ability to live outside of normal ape habitats (that is, outside of tropical, forested or semi-forested environments)
Erectines expanded their territory as they followed the animals they hunted. The earliest Erectines found outside of Africa (those from the site of Dmanisi, Georgia), are found with other animals that today are only found in Africa.
Erectines, as hunters, must have had large territories. (It takes a much larger territory for a lion to find enough gazelle to eat, than it takes for a gazelle to find enough grass to eat). As one territory filled up, groups would have split and moved outward. Within an individual's lifetime, the boundaries of the species wouldn't move much, but this strategy would quickly fill up the landscape and easily move the Erectines from Kenya to Indonesia within a few hundred thousand years.
Apes do not use territory in the way described above. This type of movement may suggest a more human-like subsistence and social strategy.
More human social organization
Erectines are the first group for which we have indications that there might be a post-reproductive period in life. We discussed the grandmother hypothesis earlier in this class. Humans are cooperative breeders, and this pattern may have started with the Erectines.
Erectine Technology
Erectines used stone tools that were more sophisticated than the Olduwan tools used by earlier hominins. In Europe, Erectine technology is called Acheulean, after the site of Saint-Acheul, France, where it was first identified. Erectine stone tools look different in different parts of the world and at different times, but for the sake of simplicity, for this class, we'll just refer to all Erectine technology as Acheulean.
In general, Acheulean technology is a continuation of Olduwan technology, but with additional elements One added element of Acheulean technology is the development of the biface. This is simply a stone tool worked on both sides. Although bifaces came in a variety of shapes, the typical, diagnostic tool of this time period is the Acheulean hand ax. These hand axes are found in the western part of the Erectine range. There is some debate about what they were used for. Some theories include:
They were the "Swiss army knife" of the Paleolithic, meaning they were used for just about everything
They were tools for butchering large animals
They were digging tools for reaching roots
They were "killer Frisbees" (this isn't a very serious idea, but I like saying "Killer Frisbee Theory")
Of these theories, the first and second are the mostly likely, based on microwear studies (looking at the traces left on tools by their use) and experimental studies.
Compared to the earlier Olduwan tools, Acheulean tools were more complex, came in a wider variety of types and styles, and changed more across time and space. In other words, there is some evidence that these tools were more important to the Erectines than tools were to the Habilines.
Species of Erectines:
Whether there are multiple species of Erectines, or only one, is a matter of debate. Furthermore, those researchers who believe the fossil record shows enough variability to encompass multiple species (Splitters - honestly, that's a technical term) disagree on how many species are represented. Lumpers consider all of the Erectine fossils to represent a single species, just with variation across time and space.
Depending on what degree of lumper or splitter you're talking to, the species names are used in the following ways:
There is one other controversial species of Erectine, and that is _Homo floresiensis_, aka "The Hobbit". (Actually, we're not supposed to call it "The Hobbit" because the movie producers threatened to sue some archaeologists who used that title for a talk, so instead I'll call it Homo floresienses. Not quite as catchy.) This species is found only on the Indonesia island of Flores and is known for a) have a brain the size of a chimp; b) being extremely short; and c) dating to the last 200,000-50,000, which is recent for an Erectine, even in Asia. There is on-going debate over this species, with some anthropologists believing it to be a unusual modern human, while others (the majority now) believe it to be an offshoot of Homo erectus.