Humans have always wondered the big questions, "Who am I? Where have I come from? Where am I going?" It's part of human nature. It's perhaps the underpinnings of religion.

Meat reared on land matures relatively quickly, and it takes only a few pounds of plants to produce a pound of meat.

By the end of the 20th century, up to 90 percent of the sharks, tuna, swordfish, marlins, groupers, turtles, whales, and many other large creatures that prospered in the Gulf for millions of years had been depleted by overfishing.

We are depleting this immense diversity and abundance of life, and it matters tremendously for the future of the planet.

There are a lot of smart creatures out there. Dolphins, elephants, and whales are smart. And there are some really smart birds. I know some really intelligent fish. But they cannot know what humans know and are incapable of inflicting as much damage.

Globally sharks have been killed for their fins, for their cartilage, for their livers, for their meat. But mostly what has driven some species of sharks to near extinction - including the hammerhead shark - is the new luxury taste for shark fin soup.

Everybody can make choices that will make peace with the natural world.