New possibilities for slowing or even reversing the ageing process have been raised by a study, published in the journal Cell this week, which seems to show that genetics rather than tissue damage is the reason animals grow old.

    Conventionally, scientists have argued that ageing is the inevitable consequence of wear and tear on cells and tissues over time: toxins, ionising radiation, disease and stress all play a part in contributing to decline and death. 

    Now a team under Stuart Kim at Stanford University, working on minute nematode worms, has found that hundreds of genes implicated in the ageing process are turned on by a biological switch called elt-3, which becomes more abundant as the animal grows older.

    The scientists tried to age the worms artificially by subjecting them to stresses such as heat and radiation but none of these had any effect on the ageing genes. Prof Kim concluded that the higher level of elt-3 in older animals is the result of control mechanisms gone wrong, something he calls “developmental drift”. 

    If ageing is not the result of chemical catastrophe but driven by changes in regulatory genes, it could, in theory at any rate, be slowed down or stopped. Prof Kim cannot yet say whether developmental drift occurs in humans. 

    《细胞》杂志(Cell)上周刊登的一项研究提出了减缓甚至扭转衰老过程的新可能性。该研究显示，动物变老是由遗传学原因而非组织受损造成的。

    科学家们传统上认为，老化是细胞和组织长期磨损和破裂的必然结果：毒素、电离辐射、疾病和压力都会促使动物衰老和死亡。

    现在，由斯坦福大学(Stanford University)的斯图尔特•金(Stuart Kim)带领的一个小组，正在对微小的线虫展开研究。他们发现，一种被称为ELT-3的生物学开关能够启动数百个涉及老化过程的基因，而当线虫变老时，ELT-3变得更加丰富。

    科学家们尝试人为使这些线虫变老。他们让线虫受到热和辐射等压力，但是这些都不能对涉及老化过程的基因产生影响。金因此得出结论：越老的动物，其ELT-3的丰富度越高，而这是控制机制出错的结果。他称这种现象为 “发育漂变”(Developmental Drift)。

    如果老化不是化学过程造成的灾难结果，而是由于控制它的基因发生了改变，那么从理论上说，在任何水平上，老化速度都可以被减缓甚至停止。但是金还不能确定，发育漂变是否也出现在人类身上。