There are several more plausible alternative explanations for how Homo erectus managed to turn up in Asia so soon after its first appearance in Africa. First, a lot of plus-or-minusing goes into the dating of early human remains. If the actual age of the African bones is at the higher end of the range of estimates or the Javan ones at the lower end, or both, then there is plenty of time for African erects to find their way to Asia. It is also entirely possible that older erectus bones await discovery in Africa. In addition, the Javan dates could be wrong altogether.
直立人为什么距在非洲首次出现不久就已在亚洲现身，关于这一点，还有几种解释似乎也不无道理。首先，测定早期人类化石年代的时候有很大的误差，如果非洲化石的实际年代比测定的结果早，如果爪哇人化石比测定的年代晚，或者两种可能同时并存，那么非洲直立人就有足够的时间迁移到亚洲3年代更久远的非洲直立人完全有可能还未被发现。而且，爪哇人的年代有可能根本不正确。

Now for the doubts. Some authorities don't believe that the Turkana finds are Homo erectus at all. The snag, ironically, was that although the Turkana skeletons were admirably extensive, all othererectus fossils are inconclusively fragmentary. As Tattersall and Jeffrey Schwartz note in Extinct Humans, most of the Turkana skeleton "couldn't be compared with anything else closely related to it because the comparable parts weren't known!" The Turkana skeletons, they say, look nothing like any Asian Homo erectus and would never have been considered the same species except that they were contemporaries. Some authorities insist on calling the Turkana specimens (and any others from the same period) Homo ergaster. Tattersall and Schwartz don't believe that goes nearly far enough. They believe it wasergaster "or a reasonably close relative" that spread to Asia from Africa, evolved intoHomo erectus, and then died out.
现在疑问出现了：一些权威不认为图尔卡纳化石是直立人。问题在于，图尔卡纳骸骨尽管相当完整，可是其他直立人的骸骨却残缺不全。正如塔特萨尔和杰弗里·施瓦兹在《绝种的人类》一书中所描述的那样，大多数图尔卡纳骸骨“不能和与它相近的任何种类的化石相比较，因为其他种类的化石根本没有被发现”。他们认为，除去生活在同一时期这一点，图尔卡纳骸骨与任何亚洲直立人根本没有任何相似之处，绝不应该被视为同类。一些权威坚持把图尔卡纳种属（以及其他同一时期的任何种属）称做匠人。塔特萨尔和施瓦兹认为这还不够。他们相信正是这种匠人“或匠人的一种近亲”从非洲迁移到了亚洲，并进化成直立人，而后就灭绝了。