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Matters grew murkier still in 2001 and 2002 when four exceptional new specimens were found. One, discovered by Meave Leakey of the famous fossil-hunting family at Lake Turkana in Kenya and called Kenyanthropus platyops ("Kenyan flat-face"), is from about the same time as Lucy and raises the possibility that it was our ancestor and Lucy was an unsuccessful side branch. Also found in 2001 were Ardipithecus ramidus kadabba, dated at between 5.2 million and 5.8 million years old, and Orrorin tugenensis, thought to be 6 million years old, making it the oldest hominid yet found—but only for a brief while. In the summer of 2002 a French team working in the Djurab Desert of Chad (an area that had never before yielded ancient bones) found a hominid almost 7 million years old, which they labeled Sahelanthropus tchadensis. (Some critics believe that it was not human, but an early ape and therefore should be called Sahelpithecus.) All these were early creatures and quite primitive but they walked upright, and they were doing so far earlier than previously thought.
2001-2002年间，发现了4块奇异的新化石，事情变得更加扑朔迷离。这4块化石，一块发现于肯尼亚的图尔卡纳湖，它是由米芙·利基（她的家族以寻找化石闻名）发现的，后来被称为扁睑肯尼亚人。他生活的时期与露西大体相同，他的出现增加了这样一种可能性，即他是我们的祖先，而露西仅仅属于一个已经灭绝的分支。 2001年还发现了地猿始祖种家族祖先亚种，其生活时间在580万年前到520万年前；以及原初人土根种，其生活时间可能在600万年前。后者成为已发现的最早的人科动物——但是这一记录只保持了很短的时间。2002年夏天，一支法国考古队在乍得德乍腊沙漠（一个从未发现过古代化石的地区），发现了—块距今700万年前的人科动物，他们给它取名为撒海尔人乍得种（一些人认为这不是人类，而是早期的类人猿，因此应该被称做荒漠草原猿）。所有这些动物的年代都非常久远，非常原始，但是他们都会直立行走。他们这样做的时间，比以前想像的还要久远。
米芙·利基
Bipedalism is a demanding and risky strategy. It means refashioning the pelvis into a full load-bearing instrument. To preserve the required strength, the birth canal must be comparatively narrow. This has two very significant immediate consequences and one longer-term one. First, it means a lot of pain for any birthing mother and a greatly increased danger of fatality to mother and baby both. Moreover to get the baby's head through such a tight space it must be born while its brain is still small—and while the baby, therefore, is still helpless. This means long-term infant care, which in turn implies solid male-female bonding.两足直立行走行是一种需要技能而又风险很大的变化。这意味着必须改变骨盆构造，使其承受身体的全部重量。为了保持足够的支撑力量，女性的生殖道必须变得相对狭窄。这种变化导致三种结果，其中两种在很短时间内就会出现，另一种则要更长时间才会显现出来。首先，这意味着母亲生产时的痛苦加剧，而且大大增加了母亲和婴儿死亡的危险性。其次，婴儿的头部要想顺利通过狭窄的生殖道，就必须在脑仍然比较小的时候降生——因此，新生婴儿仍需要得到父母的呵护。这意味着抚养他们需要很长的时间，这又意味着男人和女人之间的关系要很牢固。
