Does morality evolve? for instance in biblical times it was acceptable for men to marry more than one wife.?

Yeah -- it almost seems as if God is restricted by whatever is culturally en vogue at the time. Slavery was normal for the Israelites, so God allowed it because he didn't want to rock the boat by forbidding it. Polygamy was normal for the Israelites, so God allowed it because he didn't want to rock the boat by forbidding it. That goes for genocide, stoning, marriage by kidnapping, blood sacrifice, etc., etc.

So if gay marriage is part of our culture, does that mean God will allow it so as not to rock the boat?

You don't have to look to Biblical times to see that morality is constantly evolving and that it varies across cultures. A simple example is that in the late 60's to early 80's the thought that interracial marriage were "immoral" was challenged and now very few people even notice "mixed couples". A similar change during the same time period dealt with divorce, prior to that time couples that divorced were treated as social pariahs. Other examples include associating hair length with morality even though "acceptable" male hair length has varied greatly over the last several hundred years.

These are just a few recent examples, but history is full of morality changing over time. The major lesson that should be learned from this is that morality is not absolute nor can an effective moral system be rule based. For example, as soon as you say "Don't kill/murder" situations arise where killing in not only needed but could be considered a correct moral action.

Customs evolve, morality doesn't. What was objectively wrong 10,000 years ago will be wrong in 10,000 more years.

ON POLYGAMY: the following is from http://www.catholic.com/thisrock/2001/0110qq.asp

On the subject of polygamy, Scripture indicates that for a time God did tolerate this practice during the Old Testament. However, it was portrayed even then as a negative thing. When Scripture describes the domestic life of polygamists, it brings out consistently the negative effects of polygamy—jealousy, taunting, conflict, favoritism—as different wives and children struggle for position within the family. (Take for example the strife between the wives of Abraham, Jacob, or Elkana; see Gen. 21, 29–30, 1 Sam. 1).

The problems were so clearly recognized that, even if there was not then a flat-out prohibition on the practice, there had to be special legislation concerning polygamy. Thus a husband playing favorites among his wives was not allowed to deprive the children of his first wife their inheritance rights in favor of the children of a more recent wife (Deut. 21:15–16). Kings in particular were forbidden to multiply wives to themselves (Deut. 17:17). Unfortunately, this prohibition was often not followed.

As time progressed, the problems with polygamy became more and more obvious, and it stopped being practiced.

The clincher came in the time of Christ, when Jesus indicated that marriage was to be restored to the state God had intended in Genesis 2.

the final of adult men are people who're sturdy to their better halves.. i'm fortunate I actual have a sturdy guy. He facilitates me lots. He works 12 hours an afternoon and could come living house and help sparkling or prepare dinner etc... basically factor i actual ought to do is look after my son..... while i'm unwell my husband will wake no count what time and he under no circumstances complains... Allah(swt) has certainly blessed me with a gorgeous better half.

In the old testament there is several mentions of men who married more than one women starting in Genesis and throughout serveral several several books in the old. God did not condem these men but it is certainly not God's desire for us. Throughout the Bible it teaches us God's desire for us as far as marriage goes so, to start from the beginning-

Genesis 2:24: for this reason a man shall leave his father and his mother and be joined to his wife and they shall become one flesh.

(Doesn't read wives, or plural flesh.)

I can go on and on from old through new but I'll go on and on. Since your question refers to old, I'll just point you to this particular verse.

There are still countries with polygamy. There are place where slavery still exists, even if the western world refuses to call it what it is. Don't confuse morality, culture and evolution.

I don't think evolve is the word, but it develops, grows and changes, certainly.