Why are all other hominids dead?

[Calpalned]

5) I know that other species of hominids die

out due to competition with better species. As a result, it is

understandable how Homo erectus, heidelbergensis and neanderthals

went extinct. However, Austrolopithecus and Ardipithecus, correct me

if I'm wrong, still lived mostly in the forest. In fact, from what I

have read, both groups of hominids seem like chimpanzees who could

naturally walk upright. Why did they all die out?

 

[Simon Bridge]

...other species of hominids die out due to competition with better species...

Why "better"?
The rest of the question is phrased to include other assumptions... i.e..
What makes you think it was competition with other species that lead to the extinction rather than, say, climate change or in-breeding?
What makes you think that "living in forest" should lead to the species surviving?
What makes you think that no hominid (i.e. besides us) species did not survive to modern times?

Properly phrasing the question is the first step in scientific inquiry.

What have you done to investigate these questions so far?
i.e. ave you seen: http://en.wikipedia.org/wiki/Neanderthal_extinction - at least?

 

[DiracPool]

Calpalned, all of these questions of yours can really just be put under the title Physical Anthropology 101. If you studied that, you'd know that the answers to most of your questions are not yet set in stone (pardon the pun). The cladistic picture is a continually changing dynamic, as it relies heavily on archaeologists finding rare hominin artifacts. Case in point, we don't use the term "hominid" to refer to Homo erectus, heidelbergensis and neanderthals, Austrolopithecus and Ardipithecus. We use "hominin."

http://australianmuseum.net.au/hominid-and-hominin-whats-the-difference

Other definitions change too as new evidence comes in. I'm working on a paper right now about the domestication of fire in hominins and I have to routinely navigate the cladistic hierarchy in order get my dates and my hominoids straight. A colleague of mine who's a primatologist and a cladistics expert told me to stop referring to this collection of species as "Homo erectines" as I used to do and just use the term Homo erectus, keep it general. I'm taking her advice.

 

[mes314159]

Also note that the climate of Africa (for example) was not unchanging but has varied over the past several million years. Total forest coverage versus open grassland has likewise varied over time, which may be relevant for preferred survival of some species of hominins versus others. It's also the case that (in general) "monkeys" are a much more successful group worldwide than "apes" currently, but this was not necessarily true in the past. Changes in species (or supra-species) populations over time are not easy to justify or predict.