Tomato's Tough Brother

Like the tomato it's growing next to, my Solanum atropurpureum has started forming fruits. The family resemblance is undeniable between the flowers and fruits. But the resemblance ends at the leaves and stem. Unlike the tomato, S. atropurpureum is covered with thorns. Even the leaves have sharp, purple needles protruding stiffly from their upper and lower surfaces. I'm guessing that in the wild this plant isn't grazed much.