This is false.
It was understood that male and female were needed for procreation - but we have evidence from around the world, - of ancient same-sex marriage.
Here are a few.
According to the midrash Sifra, traditionally attributed to Rabbi Hiyya, a bit after 200 CE, the Egyptians and Canaanites had same sex marriage.
There are also pictures of same sex couples in ancient Egyptian wall art.
We know that ancient Chinese men and women married same-sex..
Same with some tribes in countries in Africa - right up to today.
Both North American and South American tribes had same-sex marriage, - some to this day.
At least two of the Roman Emperors were in same-sex marriages. The first Roman emperor to have married a man was Nero, who is reported to have married two other men on different occasions. Nero "married a man named Sporus in a very public ceremony... with all the solemnities of matrimony, and lived with him as his spouse" A friend gave the "bride" away "as required by law." The marriage was celebrated separately in both Greece and Rome in extravagant public ceremonies. The emperor Elagabalus married an athlete named Hierocles in a lavish public ceremony in Rome amidst the rejoicings of the citizens.
http://en.wikipedia.org/wiki/History_of_same-sex_unions
And though Christians today are trying to claim these aren't marriages -
"A same-sex marriage between the two men Pedro Díaz and Muño Vandilaz in the Galician municipality of Rairiz de Veiga in Spain occurred on April 16, 1061. They were married by a priest at a small chapel. The historic documents about the church wedding were found at Monastery of San Salvador de Celanova." - Carlos Callón. "Callón gaña o Vicente Risco de Ciencias Sociais cun ensaio sobre a homosexualidade na Idade Media"
"At St. John Lateran in Rome (traditionally the Pope's parish church) in 1578, as many as thirteen same-gender couples were joined during a high Mass and with the cooperation of the Vatican clergy, "taking communion together, using the same nuptial Scripture, after which they
slept and ate together" according to a contemporary report. Another woman to woman union is recorded in Dalmatia in the 18th century.
Prof. Boswell's academic study is so well researched and documented that it poses fundamental questions for both modern church leaders and heterosexual Christians about their own modern attitudes towards homosexuality."
*