Hominid Inter-breeding

Written by Robert Bruce Baird

'Kenyanthropus platyops': - Perhapsrepparttar 6,000,000 year old men found by a maverick who went behindrepparttar 143520 authorities back atrepparttar 143521 Olduvai Gorge will be proven to actually not be outsiderepparttar 143522 australopithecine lineage. Butrepparttar 143523 Leakey family has found a 3.5 million year old human that definitely is, and it was announced after I had writtenrepparttar 143524 things related hereto earlier in this effort. I love how these synchronicities occur and how much there is for us to know about ourselves. "The ‘Gang' Hits Again Those famed Leakey fossil hunters add a new limb to our family tree - by Simon Robinson, Nairobi.

Like other members ofrepparttar 143525 famous 'hominid gang',repparttar 143526 sharp-eyed fossil hunters employed by paleontology's Leakey family, Justus Erus spends three months a year scouringrepparttar 143527 dry, bone-rich riverbeds around Lake Turkana, in northern Kenya. It is a scrubby, desolate landscape, whererepparttar 143528 people are desparately poor and gun-toting young men are a menacing presence. But it is hallowed ground to scientists because ofrepparttar 143529 clues it offers to early human history. Still, even after five years, Erus, a 30-year-old Turkana tribesman, had scored nary a hit-just bits of animal bones and teeth.

Then one scorching morning duringrepparttar 143530 final week ofrepparttar 143531 gang's explorations in August 1999, at a site called Lomekwi, Erus noticed a white object, just a cm or two across, sticking out of a patch of brown mudstone. 'I thought maybe it was (the bones of) a monkey,' he says. Beckoningrepparttar 143532 expedition's co-leader, Meave Leakey, wife and daughter-in-law, respectively, of Richard and Louis Leakey and renowned in her own right, he asked her opinion. By nightfall they realized that they had uncoveredrepparttar 143533 partial remains of a humanlike skull.

The fossil turned out to be a totally new prehuman species and last week reignited one of paleontology's greatest debates: Did we evolve in direct steps from a common apelike ancestor between 6 million and 4 million years ago? Or didrepparttar 143534 human family tree sprout branches, some of which petered out? {No integration of Mungo Man,repparttar 143535 6,000,000 year old find,repparttar 143536 Black Skull or many other possibilities!}

Inrepparttar 143537 past 20 yearsrepparttar 143538 Leakeys and others have dug up overwhelming evidence showing that between 2.5 million and 1 million years ago,repparttar 143539 then lush woodlands and savannas of eastern Africa-where our family tree first took root-wererepparttar 143540 habitat of rival species, most of which were evolutionary dead ends. But what about before that? Paleontologists have generally agreed that there was just one hominid line, beginning with a small, upright-walking species known as 'Australopithecus afarensis', most famously represented by 'Lucy'., a remarkably complete (about 40%) skeleton found in Ethiopia in 1974.

Now {Ha!} that view is being challenged. The new skull, described by Leakey and six colleagues, including her and Richard's daughter Louise, 29, in 'Nature' last week, pushesrepparttar 143541 presence of co-existing species back another million years, to between 3.5 million and 3.2 million years ago. That's right in Lucy's time. Yet it is so different from Lucy that they assign their fossil, which they call 'Kenyanthropus platyops', or 'flat- faced man of Kenya', to a new genus, or grouping of species. 'This means we will have to rethinkrepparttar 143542 early past of hominid evolution,' says Meave Leakey, head of paleontology atrepparttar 143543 National Museum of Kenya. {Who didn't wantrepparttar 143544 Dalhousie professor digging uprepparttar 143545 6,000,000 year old bones onrepparttar 143546 Yale site, that he says aren't australopithecine, to upstage them.} 'It's clearrepparttar 143547 picture isn't as simple as we thought.' Even Lucy's discoverer Donald Johanson, director ofrepparttar 143548 Institute of Human Origins at Arizona State University, concurs. 'This is a reminder that there are probably a lot more species out there,' he says.

Drought Defined

Written by Chris Orr

Drought is usually talked about as single event. In reality, there are two types of drought: agricultural and hydrologic. Drought is further defined by its duration.

The earth's water or hydrologic cycle is a closed system, meaningrepparttar water is never lost. The rainfall we lack is a surplus somewhere else onrepparttar 143143 planet, either above ground, below ground or inrepparttar 143144 atmosphere. Rather than a spontaneous change inrepparttar 143145 weather, drought isrepparttar 143146 cumulative affect of moisture deficit. The cumulative affect also works to relieve drought.

Last year's rainfall was close to normal acrossrepparttar 143147 West River plains - certainly better thanrepparttar 143148 year before - and that is starting a positive accumulation of moisture. There is at least hope thatrepparttar 143149 drought will be overcome by additional moisture this year.

The Black Hills, however, remained very dry last year and suffered a net loss of moisture. This winter's snow-pack was minimal and they are startingrepparttar 143150 wet season with a cumulative loss of moisture. That is not a good position to be in.

Agricultural drought isrepparttar 143151 most familiar type of drought and it can vary in duration from a few weeks to a few years. Plants do not have enough moisture when this type of drought occurs. Agricultural drought can be remedied when there is enough rainfall to bring moisture several feet intorepparttar 143152 soil.

Hydrologic drought has a more significant impact on society because it affects reservoir levels as well asrepparttar 143153 amount of water in underground storage or aquifers. Hydrologic drought occurs during long dry spells and it takes a much longer time to recover. Rainfall and snowmelt must drain into reservoirs and seep deep down intorepparttar 143154 earth to reach aquifers.

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