What is meant by the statement that humans are iherently social and what evidence is there to support this

Means we are apt to socialize, to live and be together, we prefer not to live solitary lives alone and apart from others, generally.

Evidence - look around.

Yes as stated, mankind has shown from the earliest history a need to gather and be with others.

Thus the reason for early communities beyond a family setting

Inherent? Yes, it is an inherent need people have of gathering with others. It is not only a need for mutual assistance which causes this, but a real psychological need which if not satisfied can lead to both mental and physical illness. This is in contrast to the leopard and tiger which prefer to be mostly solitary until the mating season.

BTW
That's why isolation is used as punishment in prison and at other restrictive institutions:
http://av.rds.yahoo.com/_ylt=A9ibyJ0lAItE8VMBc051CqMX;_ylu=X3oDMTBxMmNlbTd lBHBndANhdl9uZXdzX3Jlc3VsdHMEc2VjA3Ny/SIG=13puri631/EXP=1150046629/**http%3a//www.democratandchronicle.com/apps/pbcs.dll/article%3fAID=/20060608/NEWS01/606080345/1002/rss01

It means we were designed to need each other. But this sounds somewhat akin to homework, in which case you need to do your own research maybe? :)