stylistic:tone
Uses

Kohn and Mithen independently arrived at the explanation that symmetric hand axes were favoured by sexual selection as fitness indicators. Kohn in his book As We Know It wrote that the hand axe is "a highly visible indicator of fitness, and so becomes a criterion of mate choice." Miller followed their example and said that hand axes have characteristics that make them subject to sexual selection, such as that they were made for over a million years throughout Africa, Europe and Asia, they were made in large numbers, and most were impractical for utilitarian use. He claimed that a single design persisting across time and space cannot be explained by cultural imitation and draws a parallel between bowerbirds ' bowers (built to attract potential mates and used only during courtship) and Pleistocene hominids ' hand axes. He called hand axe building a "genetically inherited propensity to construct a certain type of object." He discards the idea that they were used as missile weapons because more efficient weapons were available, such as javelins. Although he accepted that some hand axes may have been used for practical purposes, he agreed with Kohn and Mithen who showed that many hand axes show considerable skill, design and symmetry beyond that needed for utility. Some were too big, such as the Maritime Academy handaxe or the "Great Hand Axe" found in Furze Platt, England that is 30.6 cm long (other scholars measure it as 39.5 cm long). Some were too small - less than two inches. Some were "overdetermined", featuring symmetry beyond practical requirements and showing evidence of unnecessary attention to form and finish. Some were actually made out bone instead of stone and thus were not very practical, suggesting a cultural or ritual use. Miller thinks that the most important clue is that under electron microscopy hand axes show no signs of use or evidence of edge wear. Others argue that little evidence for use-wear simply relates to the particular sedimentological conditions, rather than being evidence of discarding without use. It has been noted that hand axes can be good handicaps in Zahavi 's handicap principle theory: learning costs are high, risks of injury, they require physical strength, hand-eye coordination, planning, patience, pain tolerance and resistance to infection from cuts and bruises when making or using such a hand axe.