Studies of birds who mate for life and those who don't reveal lots of unsuccessful male birds dying early of disease. . I hesitate to draw any 'how tos' from the animal kingdom when it comes to mankind and would recommend looking at how we used to do things for examples of things that work - they're already human-tested. . My take on marriage is that even if it doesn't seem to be as beneficial as it used to on the individual level it's still extremely good for society as a whole.

they also eat their young.

Happiness is a matter of perspective. Some people will say that the traditional family is the healthiest/most functional way to live. Others won't. I personally don't think so, especially considering the number of first time marriages that end in divorce. Throw in the fact that people are afraid of change and it's easy to see why people at least try to take the traditional method. . The bottom line is that for some people, that method will work while others it won't. +3

Many of us humans seem to have a desire to be in some kind of long-term partnership, and it's not always connected with passing on our genes. I don't think marriage is necessary for this, it's more of a social custom than anything else, and has become convenient due to how our society operates. If you want to have children, forming a family group with two parents makes practical sense because (in theory at least) it results in them having more than one person to care for them, and supply their needs. I don't know if other animals feel emotions the way humans do, but it would seem that some of them do form relationships for reasons other than just procreation. There's some evidence, for example, that elephants show complex emotional attachments to each other, and certainly some species mate for life. I think perhaps the reason humans operate the way we do is because, for some reason or other, we've developed needs beyond the basic drive to pass on our genes. For many of us, having children isn't important, or is something we even actively don't want, which means we've removed the whole evolutionary point of having a mate. In that case, having a partner is the end in itself, but the reason for getting married is, I think, purely a society-driven one.

..it is the healthiest way..read some studies..children thrive when there is a nuclear family structure..and that creates functional and healthy adults