A common thread.

All suffer,it could become biggest common thread and for its control ,human making efforts since start of civilization and at least partially been able to devise some recurring events ,functions,festivals and social structures which to masses provide at least few moments of joy,togetherness with bitterness sidelined.
Fear is supposed to be another big common thread to joint many loose ends ,real or imaginary,hypothetical or exaggerated lead to dilute differences and complaints,and start chanting same lines in all conversation/media etc by which perfect impression of unity,compassion merge in common cause which provide relief to all concerned. 
Where minimum security,stability gets established by system then common thread more profoundly bind society,in other scenario all work for their individual goal,rest becomes less important.
Leaders need to rake up issues which can fire imagination of masses,and cause major changes in perception of masses ,thereby yielding major growth,development dividends for benefits of all.
With changing times common threads had been varying,in olden days loyalty to individual was supreme common thread,now its more to institutions now.
A common purpose/issue bind humanity,virtual world may also contribute in it significantly with times and with access available to all.
The humans are all a single species ,unlike animals who are different totally and all are categorized in broad category of animals.

Each type of animal is a different class and they have their own genetic similarities which is reflected in their basic nature.

The human is a single race ,yet like animals we have created so many classes and differences and tend to believe that one is different from others.its the capacity of human mind to understand the languages spoken around him.

The humans are segregated on the basis of their faith ,their continent,their economic status etc.

Its our assumption about the superior life that one is enjoying,the huge scientific development in some part of world is not matched by similar investment in understanding the basic man,about his real need,about his real purpose to eliminate all suffering.

On the other hand human formed groups and developed some distinct culture of it and strives to achieve wealth and all materialistic things,in this pursuit some had been successful but the threats are always mounting  ,the lack of cohesive vision etc which caused deep smoldering.

The wheel of human history moved slowly earlier but now there speed has been accelerated by the humans itself and it could be taken for granted that next century may consist  of different human even by default.