Life at any cost?

Wandering around Zagreb's bucolic botanical garden today, my gently roving eye fell on the tree in the foreground of this picture.

I noticed the pale yellow young stems just above the trunk, with their needle-like leaves looking very much like defensive weapons, which they may well double as for all I know, and it occurred to me just how much this species had had to differentiate from trees in mild, wet climates and environments lacking large plant eaters in order to find an ecological niche. 

The thick, gnarled bark of the trunk, plus the rigid self-censorship of the spikey leaves. So far from the unconcerned gentle reach and sweep of northern European trees.

I may have been anthropomorphising somewhat, but I was struck by how much carefree abundance this species had been prepared to lose (from a genetic ancestor that I assume had life relatively easy), and how much stressful effort it was prepared to exert, in order to live. 

Gone are the genes for openness and abundance, while genes for toughness and restriction have appeared or been ramped up. 

And trees can feel stress, as the garden's visitor information detailed: exotic trees have shorter lives in the botanic garden than they would in the wild, for example, because of the stress of the unfitting climate. 

What carefree genes have been cast off or turned down in humans during our evolutionary history, I wonder, and what aggressive and ugly ones amped up? And in future? 

What stunted creatures are we? 

And how powerful is the drive for life!