<\/p>\n
<\/p>\n
El autor ve o mejor dicho imagina el antepasado com\u00fan del caballo. Nada que Lamarck no hubiese hecho mejor d\u00e9cadas antes.<\/p>\n
<\/p>\n
<\/p>\n
<\/p>\n
244<\/em><\/p>\n \u00a0<\/em><\/p>\n What now are we to say to these several facts? We see several distinct species of the horse genus becoming, by simple variation, striped on the legs like a zebra, or striped on the shoulders like an ass. In the horse we see this tendency strong whenever a dun tint appears\u2014a tint which approaches to that of the general colouring of the other species of the genus. The appearance of the stripes is not accompanied by any change of form, or by any other new character. We see this tendency to become striped most strongly displayed in hybrids from between several of the most distinct species. Now observe the case of the several breeds of pigeons: they are descended from a pigeon (including two or three sub-species or geographical races) of a bluish colour, with certain bars and other marks; and when any breed assumes by simple variation a bluish tint, these bars and other marks invariably reappear; but without any other change of form or character. When the oldest and truest breeds of various colours are crossed, we see a strong tendency for the blue tint and bars and marks to reappear in the mongrels. I have stated that the most probable hypothesis to account for the reappearance of very ancient characters, is\u2014that there is a TENDENCY in the young of each successive generation to produce the long-lost character, and that this tendency, from unknown causes, sometimes prevails. And we have just seen that in several species of the horse genus the stripes are either plainer or appear more commonly in the young than in the old. Call the breeds of pigeons, some of which have bred true for centuries, species; and how exactly parallel is the case with that of the species of the horse genus! For myself, I venture confidently to look back thousands on thousands of generations, and I see an animal striped like a zebra, but perhaps otherwise very differently constructed, the common parent of our domestic horse (whether or not it be descended from one or more wild stocks) of the ass, the hemionus, quagga, and zebra.<\/em><\/p>\n \u00a0<\/em><\/p>\n Ahora bien: \u00bfqu\u00e9 diremos de estos diferentes hechos? Vemos varias especies distintas del g\u00e9nero caballo que, por simple variaci\u00f3n, presentan rayas en las patas como una cebra, y rayas en el lomo como un asno. En el caballo vemos esta tendencia muy marcada siempre que aparece un color bayo, color que se acerca al de la coloraci\u00f3n general de las otras especies del g\u00e9nero. La aparici\u00f3n de rayas no va acompa\u00f1ada de cambio alguno de forma ni de ning\u00fan otro car\u00e1cter nuevo. Esta tendencia a presentar rayas se manifiesta m\u00e1s intensamente en h\u00edbridos de algunas de las especies m\u00e1s distintas. Examinemos ahora el caso de las diferentes razas de palomas: descienden de una especie de paloma -incluyendo dos o tres subespecies o razas geogr\u00e1ficas- de color azulado con determinadas fajas y otras se\u00f1ales, y cuando una casta cualquiera toma por simple variaci\u00f3n color azulado, estas listas y se\u00f1ales reaparecen invariablemente, sin ning\u00fan otro cambio de forma o de caracteres. Cuando se cruzan las razas m\u00e1s antiguas y constantes de diversos colores, vemos en los h\u00edbridos una poderosa tendencia al color azul y a la reaparici\u00f3n de las listas y se\u00f1ales. He sentado que la hip\u00f3tesis m\u00e1s probable para explicar la reaparici\u00f3n de caracteres antiqu\u00edsimos es que en los j\u00f3venes de las sucesivas generaciones existe una tendencia a presentar el car\u00e1cter perdido desde hace mucho tiempo, y que esta tendencia, por causas desconocidas algunas veces, prevalece. Y acabamos de ver que en diferentes especies del g\u00e9nero caballo las rayas son m\u00e1s manifiestas, o aparecen con m\u00e1s frecuencia, en los j\u00f3venes que en los adultos. Llamemos especies a las razas de palomas, algunas de las cuales han criado sin variaci\u00f3n durante siglos, y \u00a1qu\u00e9 paralelo resulta este caso del de las especies del g\u00e9nero caballo! Por mi parte, me atrevo a dirigir confiadamente la vista a miles y miles de generaciones atr\u00e1s, y veo un animal listado como una cebra, aunque, por otra parte, construido quiz\u00e1 de modo muy diferente, antepasado com\u00fan del caballo dom\u00e9stico -haya descendido o no de uno o m\u00e1s troncos salvajes-, del asno, del hemi\u00f3n, del cuaga y de la cebra.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":" El autor ve o mejor dicho imagina el antepasado com\u00fan del caballo. Nada que Lamarck no hubiese hecho mejor d\u00e9cadas antes. 244 \u00a0 What now are we to say to these several facts? We see several distinct species of the horse genus becoming, by simple variation, striped on the legs like a zebra, or striped on the shoulders like an ass. In the horse we see this tendency strong whenever a dun tint appears\u2014a tint which approaches to that of the general colouring of the other species of the genus. The appearance of the stripes is\u2026<\/p>\n","protected":false},"author":86,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0},"categories":[467,14322,14331],"tags":[],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":4}},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/posts\/136167"}],"collection":[{"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/users\/86"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/comments?post=136167"}],"version-history":[{"count":5,"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/posts\/136167\/revisions"}],"predecessor-version":[{"id":136637,"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/posts\/136167\/revisions\/136637"}],"wp:attachment":[{"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/media?parent=136167"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/categories?post=136167"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/biologia_pensamiento\/wp-json\/wp\/v2\/tags?post=136167"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}