![]() Despite considerable progress in the understanding of syndactyly at clinical and molecular levels, fundamental questions regarding the disturbed developmental mechanisms leading to fused digits, remain to be answered. In this communication, based on an overview of well-characterized isolated syndactylies, their cardinal phenotypes, inheritance patterns, and clinical and genetic heterogeneities, a 'current classification scheme' is presented. Whereas the underlying genes/mutations for types II-1, III, IV, V, and VII have been worked out, the etiology and molecular basis of the other syndactyly types remain unknown. Most of the syndactyly types are inherited as autosomal dominant but two autosomal recessive and an X-linked recessive entity have also been described. At least nine non-syndromic syndactylies with additional sub-types have been characterized. Even within a subject, phenotype can be unilateral or bilateral and symmetrical or asymmetrical. Syndactylies exhibit great inter- and intra-familial clinical variability. It may occur as an isolated entity or a component of more than 300 syndromic anomalies. Syndactyly is one of the most common hereditary limb malformations depicting the fusion of certain fingers and/or toes. We argue that the term "syndactyly" is a misnomer because the marsupial condition only superficially resembles its name-giving human soft-tissue syndactyly. Although convergent evolution appears likely, syndactyly in Diprotodontia and Peramelemorpha may occur through homologous developmental processes. The results suggest that marsupial syndactyly originates from a constraint that is rooted in early digit ontogeny and results in evolution of the syndactylous digits as a highly integrated unit. Reports of incipient syndactyly in some marsupial clades could not be confirmed contrary to previous claims, syndactyly does not appear to impact on tarsal bone arrangement. However, this does not impact on overall locomotor adaptation patterns in the syndactylous foot as determined by analysis of locomotor predictor ratios. Syndactylous digits have virtually identical variance/covariance matrices and display heterochronic ossification timing with respect to digits IV/V. This study undertakes the first interdisciplinary characterisation of syndactyly, using variance/covariance matrix comparisons of morphometric measurements, locomotor indices, ossification sequences, and re-assessment of the largely anecdotal data on the phylogenetic distribution of tarsal/metatarsal articulations and "incipient syndactyly". Past treatments of marsupial syndactyly have not considered the implications of this unique morphology for broader issues of digit development and evolution, and the ongoing debate regarding its phylogenetic meaning lacks a broad empirical basis. #WEBBED TOES HUMAN SKIN#It is traditionally defined as a condition in which digits II and III of the foot are bound by skin and are reduced. He posits that subsisting only on “nutritionally balanced non-solid substances” could mean people end up with toothless mouths.Īnd if the Earth is plunged into an Ice Age, future generations will bigger, harier and paler, Dr Skinner says, to help improve heat retention and absorption of vitamin D.Marsupial syndactyly is a curious morphology of the foot found in all species of diprotodontian and peramelemorph marsupials. The scientist also expects changes in human evolution to occur if we ever end up colonising Mars. ![]() “Due to the cold environment of being submerged in water regularly, we would maintain a layer of ‘baby fat’ into adulthood as an insulator.” “We may evolve a tapetum lucidum, an additional layer in the retina, like cat’s eyes, that would improve our vision in low light conditions such as underwater. “Regular underwater foraging would lead to the evolution of longer fingers and toes which would then likely develop ‘webbed’ interconnecting skin to enable easier swimming,” Dr Skinner explained. He also suggests that we’ll develop cat-like eyes to help us see in underwater gloom, and that our lungs will shrink as we adapt to breathing using underwater gear. He reckons that webbed hands and feet and less body hair will help the human of the future move quickly through water as climate change forces sea levels to rise. One plucky scientist has suggested that humans could end up evolving webbed feet as a side-effect of climate change.ĭr Matthew Skinner had a think about what could happen to human evolution based on a number of possible futures. ![]()
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