During the qualifying rounds of the 1998 World Cup, Jamaica's football team, The Reggae Boys, were unbeaten at home. Jamaica's Independence Park, dubbed "The Office," became a fortress that no invading force was able to breach. Traditionally superior teams like Mexico, USA and Costa Rica were not only unable to win at The Office, they never even scored a single goal.

Mexico beat them twice at The Azteca, on one occasion pummeling them 6-0. At home, however, Jamaica's defence was impenetrable, their offence speedy and incisive. At home, The Reggae Boys refused to be defeated.

Those of us who follow sport largely accept the validity of home advantage. Teams perform better when they play at home - that is undisputable. Football teams score more goals and concede fewer when they play at home. The same is true of other sports like basketball, netball and hockey. Cricket teams make more runs and concede fewer at home, as do baseball teams. It has even been shown that Olympic athletes win more medals when the games are held in their home country.

Cricket probably differs from other sports in that the conditions in which it is played are more varied and has more of an impact than it does in most sports. The ball bounces more in Australia and South Africa, seams more in England and New Zealand, and turns more in the subcontinent. Naturally, players become adept at exploiting the conditions in which they were brought up. And so there little surprise - though this is perhaps an oversimplification - that India are traditionally known for their spinners, Australia for their pacers, and England for their medium-paced seamers.

Comfortable and confident in their environment, Australia are currently administering a fearful thrashing to their Ashes opponents. The bounce and carry on offer has gifted an advantage to the hosts speedier pacers.

But the Australian attack has been outperforming their English counterparts in other areas as well. Cricviz, a webiste that specialises in statistical analysis, has revealed that the hosts' bowlers have collectively generated more swing and extracted more seam movement than the England bowlers. This is rather surprising since swing and seam are supposed to be the specialty of the English, and their spearhead, Jimmy Anderson, is widely regarded as the most skillful swing bowler in the game.

In cricket nowadays, with players regularly visiting other countries to play T20 franchise cricket, 'A' tours, or in first-class competitions, familiarity with the gamut of playing conditions is widespread. And so if home conditions played a big role in home wins in years gone by, its effects should be now reduced.

But teams are thriving at home more than ever. In fact, according to an ESPNCricinfo article titled Bad tourists from 2015, "Over the last ten years, teams have lost more than twice as many matches as they have won when playing overseas, a record which is much worse than in earlier years."

It has been long assumed that crowd support at home matches had much to do with the phenomenon of home advantage. Indeed, it has been established that crowd noise has an effect on the officiating of games, where referees and umpires unconsciously favour the home team.

But the effect of crowd size and crowd noise are not as significant as we may think. Studies have shown, for example, that home advantage remains firmly intact for football games contested before totally empty stands. Additionally, for same-stadium derbies (matches between teams using the same stadium for home games) there is no discernible home advantage even though the side hosting the encounter usually has significantly more support in the stands.

Therefore, if it's not the size of the crowds nor familiarity with home conditions, what accounts for home advantage? Why are teams more likely to win when playing at home?

It turns out that home advantage might be largely due to players striving harder - unconsciously mind you - to defend their home turf. Studies suggest that players see home encounters as more important than those away from home and compete accordingly. They are more aggressive at home, more focused and therefore more likely to win.

Think of someone invading your home. Do you think you'd fight even harder to hold your space than you would otherwise? Research done by Matthew Fuxjager while completing his doctoral dissertation at the University of Wisconsin, and as reported by L. Jon Wertheim and Sam Sommers in their book This Is Your Brain On Sports, indicate that territorial mice fight harder at home. Fuxjager also measured heightened levels of testosterone in mice fighting in their own cages.

Fuxjager found that the mice were more likely to win when they fought in their home cages than if they fought in other cages: "For the mice, a home fight is a more important fight. They want to protect their home turf. They want to protect their resources. They want to protect their mate and their offspring. They're more motivated, and there's a different physiological effect that comes with that."

Sportsmen are not protecting mates or offspring, of course, but could there be something primal about their tendency to compete harder at home? Could it be that India's mostly stellar home record has more to do with their mindset while playing at home rather than any advantage gained by playing in subcontinent conditions that favour spin? Could seam and swing have little to do with England's enviable home record?

We have seen that India's batsmen can be just as susceptible in home conditions facilitating spin as visiting batsmen. The England tourists won the 2012-13 series mainly due to the bowling of spinners Monty Panesar and Graeme Swann; left-arm slow bowler Steven O'Keefe spun Australia to victory in Pune a few months ago; and though they easily defeated the visiting South Africans on the 2015-16 tour, there were a few moments where the hosts showed vulnerability.

Similarly, England conditions can be just as hostile to England players as they are to visiting ones. The lowly rated West Indies recently scored a remarkable victory, in Headingly of all places, by conquering English conditions. While teams like Pakistan and Sri Lanka have won and drawn series in England in recent years.

The point is that alien conditions are not so alien anymore. And yet home advantage is more pronounced than ever. The top teams today are probably not that far apart in terms of ability. These are not the days when the West Indies or Australia were so much better than the rest that they were able to beat anybody anywhere. The small advantages therefore, such as those associated with playing at home, are more important than ever.

The team travelling to confront another is seen as an invading force that must be repelled.

The Reggae Boys seemed to run faster at The Office during the 1998 qualifiers, they tackled harder. There were trespassers at the gates trying to deprive them of their first World Cup berth. They weren't having it and refused to lose, much like the Viet Cong refusing to be defeated by the invading American forces during the Vietnam war.

Sports, said George Orwell, is "war minus the shooting." The English have sent an invading force down under to secure the Ashes. The Aussies are not having it much like the English were not having it in 2015 when battlefield came to their shores; and much like most teams who triumph against foreign aggressors.

Teams fight harder at home because they're defending their territory. Home conditions and home crowds provide some benefits, but the real reason teams win more often when playing at home probably has more to do with testosterone than anything else.