Early man development

That he and a couple of others could run a four legged hair-covered critter to exhaustion and then chow down.

Oh, yeah, and how to keep a fire going.

Joe(those two)Nation

Probably that if you throw rocks and sticks, you can drive hyenas off the body, and eat what they killed.

The toothpick !

Pepto-Bismol.

Grey Poupon mustard.

Fashion.

Language.
It probably started out as gestural symbols, grunts, and facial expression, which then likely accumulated and developed into more complicated and organized voiced syllables that compromised a greater variety of vocabulary.
It's what allowed social structures to form, and find strength and dominance in unity.
What ranks us top up there in the food chain is mainly due to our brain's evolution to enable us to invent and develop language to understand and communicate, as well as create complex social interactions.

I'm speechless.




They took the tools to me at the salon that day.

Speaking ill of your dead ancestors is a grave mistake.

I'd like to clarify that my first response is going by the title of the question which is looking for "development," rather than "discovery" written in the detail section of the question. Certainly there's a difference which should have been clarified by the author of this question, and on that note, I'd like to suggest that there is no one discovery that stands important above other discoveries, historically observing. The specific placement of a certain discovery to be "important" is highly relative to the social group living at at some time (prehistoric times with your question) and likely entailed whatever was important to the social group at that time. Survival likely what was important to the social group at prehistoric times, which likely meant that fire was the most important discovery at that time because it gave early man an edge over other animals foraging for resources in the same environment thus a higher probability of survival, as various archaeologists have confirmed.
If I were to meet a real evolution archaeologist, my first question I would ask is if whether without the discovery of fire, would Homo Erectus have the same level of environmental pressures to evolve into Homo Sapiens?

Do you mean to tell us they developed? How?

I'm sticking with running down of game perhaps in imitation of hyenas or wild dogs (or whatever pack hunting animals were thereabouts back then.)
Think about it:

in order for a pack to work you have to develop signals (verbal and otherwise) which can be understood from a distance. (Over Here!) (There he goes) (No, not that one, the one with the black ears!!)

You have to co-operative behaviors (switching off the chase with a fresh runner) .

You have to develop planning and see events before they happen (Okay, if the big one doesn't turn towards the cliff, Oom, it will be you and Sner who will make a big noise to make him go.")

Maybe early mapping ~sticks or fingers in the sand? (See, here we are. The river is right here. and here ~~~X~~~~ is where the deer were last seen.)

And there is still no more cohesive ritual for homo sapiens than bringing fresh meat to a fire and cooking it while everybody stands around and talks.

Joe(Who wants their haunch medium rare?)Nation

Well, there is, of course, the clear implication that the question posted in the o.p. refers specifically to man's role as a carnivore. So, while I agree with your opinion that the development of language is key to human evolution, I also see this claim as irrlevant to the question. Given the unusual brain capacity of that marvelous organ in our skulls, herbivores would, no doubt, have developed language just as readily. It has nothing to do with man as meat eater, which is what the o.p. refers to.

When any animal is hungry....

...that animal will strive to eat.

But I doubt that a sheep will eat, say, a lizard if there is no grass available. It will probably starve.

They ain't called "sheep" for nut'n.

Great apes, (chimps especially), use special calls when hunting together in a group. If homo erectus had been able to develop a better communication system by creating word/shouts, that would have presented a real advantage over other hunting groups AND would have provide a more secure warning system in the event of predators.

Joe(whhoooooT!)Nation

It was still easier to drive off the hyenas and steal their kill. Lions do it all the time.

I agree with Setanta. Early man may have been a carnivore but he was a lousy hunter until he learned how to use such crude weapons as sharpened sticks and throwable stones. And even then he had to rely on small game that wouldn't bite back.