--- title: Evolution: why giraffes really have long necks — a lesson of Mova's school · trees and pragmatics description: «Evolution: why giraffes really have long necks», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: An old idea said giraffes stretched their necks to reach high leaves and then passed the longer necks to their babies, but --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/) / Evolution: why giraffes really have lo… # Evolution: why giraffes really have long necks Lesson 278 of the biology course of Mova's primary school: 16 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/biology/278-evolution-why-giraffes-really-have-long-necks/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/0/) — An old idea said giraffes stretched their necks to reach high leaves and then passed the longer necks to their babies, but that is wrong: stretching your body does not change the DNA you pass on, just as a weightlifter's babies are not born with big muscles. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/1/) — The real answer: giraffe calves are born with slightly different neck lengths, and those with longer necks often got more food or won more fights, so they had more babies, who tended to have long necks too. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/2/) — Repeat that over thousands of generations and the average neck grows longer; this is natural selection, the idea of Charles Darwin and Alfred Russel Wallace. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/4/) — It also changes what is already there instead of starting fresh, so a giraffe has the same seven neck bones as you and a mouse, only much longer. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/5/) — In 1809 Jean-Baptiste Lamarck suggested that animals pass on body changes they gained by using them, such as a stretched neck; this is wrong, because stretching does not change the DNA passed on. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/6/) — Giraffes are born with slightly different neck lengths; those with longer necks often got more food or won more fights and left more babies, so over many generations the average neck grew longer. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/8/) — A giraffe has 7 neck bones, the same number as a mouse and a person; each bone is just very long, up to about 25 centimetres or more. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/9/) — The okapi, with a shorter neck and stripy legs, is the giraffe's closest living cousin; it lives in thick forest, where a short neck suits its way of life, and fossils show giraffe relatives with shorter necks. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/10/) — Charles Darwin sailed round the world on HMS Beagle from 1831 to 1836 and noticed animals on islands; he collected evidence for about 20 years before publishing On the Origin of Species in 1859. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/11/) — Alfred Russel Wallace came up with the same idea of natural selection at the same time as Darwin. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/12/) — Evolution means fitting the place you live, not getting better in general; a fish is not worse than a person, it is fitted to water, and if the place changes, the best fit changes too. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/13/) — Cave fish in Mexico live in total darkness and lost their eyes over many generations, because eyes cost energy and are useless in the dark; fish of the same species near the surface still have eyes. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/14/) — Evolution has no plan or goal; it is just which living things leave more babies in their time and place, and the result can look designed but happens step by step. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/15/) — Fossils show that early whale relatives such as Pakicetus were land mammals that walked on four legs about 50 million years ago; some whales still have tiny hip bones inside their bodies. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/16/) — The eye could evolve bit by bit: a light-sensing patch is already useful, a cup shape shows direction, a pinhole makes a picture, and a lens makes it sharp; all these stages exist in living animals today. - [17](https://md.mova.elamur.ai/free/en/corpora/school/biology/278-evolution-why-giraffes-really-have-long-necks/17/) — There are no animals with wheels, because each step of evolution must work on its own and a wheel cannot be built step by step from living parts that need blood and nerves; bacteria do have tiny spinning motors. - ← previous: [DNA simply: the recipe in every cell](https://md.mova.elamur.ai/free/en/corpora/school/biology/277-dna-simply-the-recipe-in-every-cell/) - next →: [Natural selection we can watch: moths, finches, germs and tuskless elephants](https://md.mova.elamur.ai/free/en/corpora/school/biology/279-natural-selection-we-can-watch-moths-finches-germs-and-tuskless-elephants/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)