据英国《每日邮报》近日报道，美国科学家通过修改鸡的基因，制造出类似于鳄鱼嘴而不是鸡（喙）的胚胎，从而逆转了进化过程，此举有助于科学家们发现儿童的先天缺陷。
哈佛大学的进化生物学专家阿尔哈特•阿布扎诺夫研制出了这种具有鳄鱼嘴的鸡。他在家鸡胚胎发育初期，在鸡蛋壳上开了一个小洞，随后将微小的胶质蛋白珠滴入其中，添加蛋白质珠会抑制某些分子的发育，也会阻止鸡长出某些特征。此举让家鸡控制外貌形态的“生物信号分子”的进化过程发生了逆转，使鸡胚胎在14天内，长出了鳄鱼嘴。科学家们认为，在进化过程中，鳄鱼嘴已在数百万年前的白垩纪失去。
阿布扎诺夫表示，这种“逆向”进化过程有望为科学家们修改其他DNA（脱氧核糖核酸），并使用同样方法制造出更能适应地球气候变化的物种铺平了道路。最新突破最终也有助于消除儿童的先天缺陷。
尽管由于伦理原因，科学家们没有将这种小鸡孵化出来，但阿布扎诺夫希望最终能完成这项工作，将鸡变成手盗龙（Maniraptora）。手盗龙是小型恐龙，现存于世的鸟类中，可能有数千种鸟都是它的后代。此前科学家们就认为，鸡和其它鸟类是恐龙通过一系列遗传变化进化而来。
美国蒙大拿大学的古生物学者杰克•亨尼尔正在进行同样的工作，他试图培育出一种“鸡恐龙”，这种动物具有和恐龙一样的尾巴和手。马萨诸塞大学阿默斯特分校的发育生物学家克雷格•艾伯森表示：“最新研究告诉我们，诱导某个进化过程发生逆转是一件如此简单的事情。
生物探索推荐英文原文阅读：
Rewinding evolution: Scientists alter chicken DNA to create embryo with 'alligator-like' snout
Scientists have undone the progress made by evolution by altering chicken DNA to create embryos with alligator-like snouts instead of beaks.
Experts changed the DNA of chicken embryos in the early stage of their development, enabling them to undo evolutionary progress and give the creatures snouts which are thought to have been lost in the cretaceous period millions of years ago.
The scientific revelation of 'rewinding' evolution could pave the way for scientists altering DNA in the other direction and use the same process to create species better able to adapt to Earth's climate.
It has also been claimed that the breakthrough could eventually help eliminate birth defects in human children.
Arkhat Abzhanov, an evolutionary biologist at Harvard University, developed the chickens with snouts by cutting a square hole in the shell of a chicken egg and dropping in a small gelatinous protein bead before watching the embryo develop.
The changes allowed separate molecules on the side of the face free to grow into snouts within 14 days.
Although ethical rules prevent the eggs from bring hatched, Dr Abzhanov said he hopes to complete the work one day by turning chickens into Maniraptora.
Dr Abzhanov made the changes by analysing the 'signalling molecules' which control the anatomical changes in birds and other animals.
Adding protein beads to the egg which stifle the development of certain molecules also prevents the birds from growing certain features.
Maniraptora are small dinosaurs which it is thought spawned thousands of species of birds which exist today.
Chickens and other birds are thought to have descended from dinosaurs through a series of genetic changes.
By altering the DNA of chickens to resemble alligator genes before the beak developed, Dr Abzhanov was able to change the evolutionary path of chickens so that they grew snouts instead.
Dr Abzhanov told the New Scientist: 'It looks exactly like a snout looks in an alligator [at this stage].'
Jack Horner, a leading paleontologist based at the University of Montana, is conducting similar work in an attempt to make a 'chickenosaurus' with a tail and hands similar to those of a dinosaur.
Craig Albertson, a developmental biologist at the University of Massachusetts in Amherst, said: 'Abzhanov's 'snouted' chicken provides a striking demonstration of just how easy it can be to provoke major evolutionary changes.'
