Rise of the hominids

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Protozoans, primitive animals, first appeared on our planet about 600 million years ago, according to the fossil record.  After the miracle of plant life, particularly photosynthetic forms, animal life is more of a reaction, a kind of spontaneous combustion.  Some plant forms evolved to became parasitic on other plant species, primitive analogs of strangler figs and English ivy.  Subsistence is much easier if one can simply prey on your neighbors, and in earliest warm oceans, life ran riot, a truly target rich environment.  In short order, some parasitic species developed locomotion, enabling them to eat more and reproduce more successfully. 

Evolution took care of the rest.  Within a couple hundred million years, plants and insects covered the previously barren land.  With all that plant life converting sunlight, water and soil into edible hydrocarbons, animals proliferated, converting plant hydrocarbons into energy, water and ash.  

Given the proliferation of plant eaters, it was just a matter of time before some animals evolved into carnivores, subsisting off the flesh of their neighbors.  Animal flesh contains far more digestible carbohydrates and proteins than plant food.  Carnivores can devote more body mass to muscle, tooth and nail, than can the lowly herbivore.  Such is the chain of life - each transaction is a tragic end for one living thing and sustenance for another. 

Some of these carnivores evolved into social animals.  By social, I mean possessing the instincts to form groups of individuals, not from the same nuclear family, living together permanently or semi-permanently and working together for the common good.  Coyotes and wolves are examples.  Coyotes are solitary animals that live together in nuclear families, but separately as adults.  Wolves live together in permanent packs of related and unrelated individuals.  

By 200 million years ago, a natural hierarchy of lifeforms had settled in, a continuous food chain that led from the apex predators down to the lowest plant life.  For some species in some environments, instinctive social organization worked best, for other species, solitary existence remained less risky and more productive.  Consider the medium sized Theropod dinosaurs of the Cretaceous age.  They were carnivores, probably warm-blooded.  Some paleontologists believe they lived and hunted in packs like modern-day wolves.  Because they were bipedal, they had the use of their forearms and 3-fingered hands.  Over time, as they evolved, their brains grew larger, possibly as an adaptation to enhance their social hunting skills.  A few paleontologists have gone so far as to propose these “Velociraptor” animals were on their way to making tools and starting fires.  Unfortunately, the mass extinctions at the K-T boundary eliminated most Theropods, leaving only the birds to continue the line.

This hierarchical pattern of dog eat dog continued, interrupted by the mass extinction of all terrestrial animals larger than 25 kilograms approximately 65 million years ago, but returning with the rise of mammals and birds.  There is nothing to indicate that life was very different for the mammalian apex predators of the late Tertiary period, than it was for the Theropod dinosaurs of the mid Cretaceous period 100 million years earlier.  

Somewhere around 5 million years ago a new genus, Homo, predecessors of modern humans, came into this relatively settled existence.  Because they were bi-pedal, carnivorous and social, these Hominid species, as they are called, gradually improved their tool making abilities well beyond their primate ancestors.  Living on the savannah, they preyed on large ungulates and carrion of same.  They encamped in sheltered spots, near food and water, but only for short stays of a few days or weeks at most.   

Their tool making abilities were aimed at the obvious – sharpened sticks for killing game, gourds for carrying water, stone choppers for butchering the carcasses and simple rucksacks for carrying the meat back to their camps for sharing with the women with children and old folks who depended on the hunters.  Of these supposed artifacts, only stone choppers remain as archeological evidence.  About a million years ago, some of these hominids made a giant leap forward in their tool making – fire. 

It’s highly likely they picked up on the uses for fire from their natural surroundings.  Lightning-started fires are common on the savannah.  The great leap came with the techniques needed to start fire.  Simple friction tools made of wood can be used to start a fire.  Once learned and passed on to successive generations, it changed everything.  With fire, you can roast meat, thereby sanitizing it and make it more digestible.  With fire, many tubers that were previously inedible became rich sources of hydrocarbons and other nutrients.  Most importantly, with fire and furs, hominids could thrive in seasonably cold climates.

Throughout this 5-million-year long period, the brains of the hominid grew larger, gradually in the beginning and faster during the last million years, especially the cerebral cortex and parts of the brain involving speech and abstract thinking.  No other species in the history of life on earth has grown its brain as quickly and as large as the hominids.  The combination of living in groups and a growing repertory of toolmaking skills transformed the Homo genus into the crown of creation, capable of living almost anywhere on earth and dominating all other species.

Changing climate conditions allowed several hominid species to break out of Africa as early as 1.8 million years ago.  Several other hominid species followed.  Meanwhile, about 200,000 years ago, the first modern humans, Homo sapiens appeared in Africa, obviously descended from an earlier Homo species.  By 125,000 years ago, modern humans had expanded their range to the Levant in the Near East.  By 40,000 years ago they reached Australia and Europe and the rest of Asia.  Everywhere they went; this superior species proceeded to replace the hominids that had arrived earlier.  One can imagine the brutal competition for food sources, with the smarter modern humans killing their less sophisticated competitors, and in some cases, breeding with them as their slaves.

All of the advanced capabilities we identify in modern humans are present to a lesser degree in other animals and particularly evident among our hominid predecessors.  The biggest advances we can claim for Homo are tool making (technology) and language.  With our ever larger brains and increasingly sophisticated language skills, hominids became increasingly aware of their own mental state and that of others, thereby giving rise to complex communications.

Mammalian brain size is limited by the ability of newborns to pass through their mother’s birth canal.  Among hominids, the obvious workaround is a much longer period of childhood growth.  The human cranium continues growing into the late teens.  The biological strategy at work here is the largest brain possible and an extended period of knowledge transfer from adults to children, unmatched by any other species, past or present. 

The result of this evolution is a human mental life that far exceeds that of all our predecessors.  All animals think, the more advanced species use verbal communication, some even use tools.  Human simply have more of these capabilities, far more.  We are different by degrees, not by kind, and our capabilities developed gradually.  Our hominid ancestors and their relatives had a rich mental life, but to a lesser degree than modern humans.  This evolutionary refinement of the brain, and the mind it contains, continues unabated.

So what does this mean, how should we describe our human mental condition, our minds?  It probably all began when our hominid ancestors evolved over several million years, from body posture, augmented with corresponding grunts and cries, to an actual language, with a vocabulary growing from dozens of words to hundreds that could be combined in various ways to convey thoughts, metal impressions, to other members of the social group.  It’s fair to say the typical early hominid vocabulary was originally confined to daily life, nouns for the animals they chased, verbs for the typical actions they undertook, prepositions for timing and causal relations, even place names for their encampments and home territories.  It’s also fair to conclude that singing and beating on pieces of wood, i.e., music, was part and parcel of their daily life and a clear extension of their proto-language.  By a million years before present, these essential precursors of human mental life were in place. 

Imagine a band of 25 Homo erectus individuals in this timeframe, 800,000 years before present.  They are living in a temporary encampment, near running water and timber, every few days preying on large herds of nearby big game, competing with the big cats, bears and wolves for the same food source.  Unrelated hominid bands operating nearby would be considered either enemies or prey.

Because these hominids are omnivores, some of the band, including most females and juveniles, forage daily for fruit, nuts and tubers.  Unlike their less evolved hominid ancestors, they have tools for starting campfires with deadwood - to cook food, including the otherwise useless tubers, to keep warm and light the night.  Every evening, the whole band gathers around one or more of these campfires.  They eat and engage in some discussion, the nature of which is limited only by their brain’s gradually evolving language capability and a vocabulary of no more than a few hundred words.  By comparison, the average modern human in the street has a working vocabulary of at least 1500 words and in some cases many times that.

Although primitive by modern standards, these hominids already exhibit a key characteristic of the human mind - the sharing of complex ideas among the social group.  Lions, which also live in social groups, have simple verbal and non-verbal expressions to convey commands, complaints, etc. between each other, but only certain Paleolithic hominids, among all animals at that time, were able to conduct a verbal dialog about concepts, possibilities and events, past and future. 

If we could eavesdrop on our little hominid band and their discussions, as they gathered around the campfire after a successful hunt, we would consider them to be mentally challenged compared to moderns.  Their behavior would be distinctly uncivilized, with much verbal quarreling and domestic violence.  Nevertheless, they were on a path that would eventually lead to the mental life of modern humans, that rich inner life we are so familiar with.

About 10,000 years before present, Neolithic humans in Western Asia, began to cultivate croplands and domesticate animals for food on a much larger scale than previously.  Earlier Paleolithic peoples also herded wild animals and harvested wild crops, but Neolithic peoples selectively bred their plants and animals for maximum productivity and ease of use. 

These new methods of cultivation and husbandry produced two typical cultures.  The first were pastoralists who drove large herds of domesticated ungulates from pasture to pasture, as the seasons changed.  The second were agriculturalists who began intensively planting cereal grains and other food crops in riverine flood plains.  People who were skilled at making fire and armed with stone implements could burn off brush in the late dry season and plant their grains right after the wet season.   

The agriculturists also kept domestic animals, but on a smaller scale using surplus produce and by-products.  What distinguished the agriculturalists was their need to live in semi-permanent settlements close to their cultivated food plots.  These settlements were populated by related and unrelated individuals working for a common purpose, but their communities were larger in size than previous and contemporary bands of hunter-gatherers.

In places most suited for agriculture, such as large river deltas at the temperate latitudes, these agricultural activities and the associated human settlements became increasingly sophisticated and prosperous.  Irrigation agriculture produced large crop surpluses, enough to support people engaged in vocations other than the usual herding animals and tending crops.  By 7,000 years before present, the first large towns were established in lower Mesopotamia - inhabited by merchants, tradesmen, priests and soldiers, a true civilization.

Consider how far hominids have evolved in the 5 million years since they left the forest and began running around on two legs, killing other animals with wooden spears for their dinner.  Gradually, their bodies, and especially their brains, evolved to take advantage of their ecological niche.  They became the dominant predator in savannah environments throughout the Old World.  Their use of fire resulted in physical adaptation to a diet of cooked food.  Modern humans cannot easily subsist on uncooked foodstuffs.  Hominid brains grew larger and better adapted to an enhanced social life, with its organized hunting, toolmaking and language arts.  With the advent of irrigation agriculture, their cultural development took off at an even higher pace, outstripping their physical evolution.  

We humans are a generalized species, adaptable to diverse environments.  Recently in our evolutionary history, we left behind our hunter-gatherer mode of subsistence, moving into permanent agricultural and urban settlements and a very different daily existence.  This rapid shift and our struggle to adapt, has put stress on our bodies and minds, giving rise to a host of problems and aberrant behaviors, which we will address in future posts here.  Meanwhile, next is a short essay on the key characteristics that differentiate modern humans from all other animals.